George A. Olah

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Name: Olah, George A.; George A. Olah

Organization: University of Southern California , USA

Department: Loker Hydrocarbon Research Institute and Department of Chemistry

Title: (PhD)

TOPICS

Physical Chemistry

Organic Chemistry

Chemicals
References

Efficient Reversible Hydrogen Carrier System Based on Amine Reforming of Methanol

Co-reporter:Jotheeswari Kothandaraman, Sayan Kar, Raktim Sen, Alain Goeppert, George A. Olah, and G. K. Surya Prakash

Journal of the American Chemical Society February 22, 2017 Volume 139(Issue 7) pp:2549-2549

Publication Date(Web):February 2, 2017

DOI:10.1021/jacs.6b11637

A novel hydrogen storage system based on the hydrogen release from catalytic dehydrogenative coupling of methanol and 1,2-diamine is demonstrated. The products of this reaction, N-formamide and N,N′-diformamide, are hydrogenated back to the free amine and methanol by a simple hydrogen pressure swing. Thus, an efficient one-pot hydrogen carrier system has been developed. The H2 generating step can be termed as “amine reforming of methanol” in analogy to the traditional steam reforming. It acts as a clean source of hydrogen without concurrent production of CO2 (unlike steam reforming) or CO (by complete methanol dehydrogenation). Therefore, a carbon neutral cycle is essentially achieved where no carbon capture is necessary as the carbon is trapped in the form of formamide (or urea in the case of primary amine). In theory, a hydrogen storage capacity as high as 6.6 wt % is achievable. Dehydrogenative coupling and the subsequent amide hydrogenation proceed with good yields (90% and >95% respectively, with methanol and N,N′-dimethylethylenediamine as dehydrogenative coupling partners).

Anthropogenic Chemical Carbon Cycle for a Sustainable Future

Co-reporter:George A. Olah, G. K. Surya Prakash, and Alain Goeppert

Journal of the American Chemical Society August 24, 2011 Volume 133(Issue 33) pp:12881-12898

Publication Date(Web):May 25, 2011

DOI:10.1021/ja202642y

Nature’s photosynthesis uses the sun’s energy with chlorophyll in plants as a catalyst to recycle carbon dioxide and water into new plant life. Only given sufficient geological time, millions of years, can new fossil fuels be formed naturally. The burning of our diminishing fossil fuel reserves is accompanied by large anthropogenic CO2 release, which is outpacing nature’s CO2 recycling capability, causing significant environmental harm. To supplement the natural carbon cycle, we have proposed and developed a feasible anthropogenic chemical recycling of carbon dioxide. Carbon dioxide is captured by absorption technologies from any natural or industrial source, from human activities, or even from the air itself. It can then be converted by feasible chemical transformations into fuels such as methanol, dimethyl ether, and varied products including synthetic hydrocarbons and even proteins for animal feed, thus supplementing our food chain. This concept of broad scope and framework is the basis of what we call the Methanol Economy. The needed renewable starting materials, water and CO2, are available anywhere on Earth. The required energy for the synthetic carbon cycle can come from any alternative energy source such as solar, wind, geothermal, and even hopefully safe nuclear energy. The anthropogenic carbon dioxide cycle offers a way of assuring a sustainable future for humankind when fossil fuels become scarce. While biosources can play a limited role in supplementing future energy needs, they increasingly interfere with the essentials of the food chain. We have previously reviewed aspects of the chemical recycling of carbon dioxide to methanol and dimethyl ether. In the present Perspective, we extend the discussion of the innovative and feasible anthropogenic carbon cycle, which can be the basis of progressively liberating humankind from its dependence on diminishing fossil fuel reserves while also controlling harmful CO2 emissions to the atmosphere. We also discuss in more detail the essential stages and the significant aspects of carbon capture and subsequent recycling. Our ability to develop a feasible anthropogenic chemical carbon cycle supplementing nature’s photosynthesis also offers a new solution to one of the major challenges facing humankind.

Chemical Aspects of Astrophysically Observed Extraterrestrial Methanol, Hydrocarbon Derivatives, and Ions

Co-reporter:George A. Olah; Thomas Mathew; G. K. Surya Prakash;Golam Rasul

Journal of the American Chemical Society 2016 Volume 138(Issue 5) pp:1717-1722

Publication Date(Web):January 13, 2016

DOI:10.1021/jacs.6b00343

Astrophysically observed extraterrestrial molecular matter contains, besides hydrogen and water, methane and methanol as the most abundant species. Feasible pathways and chemical aspects of their formation as well as of derived hydrocarbon homologues and their ions (carbocations and carbanions) are discussed on the basis of observed similarities with our studied terrestrial chemistry. The preferred pathway for converting extraterrestrial methane according to Ali et al. is based on CH5+ and Olah’s related nonclassical carbonium ion chemistry. On the basis of the observed higher reactivity of methanol compared with methane in various chemical reactions, a feasible new pathway is proposed for the conversion of extraterrestrial methanol to hydrocarbons, their derivatives, and carbocations together with a possible connection with methonium ion-based chemistry.

Chemical Formation of Methanol and Hydrocarbon (“Organic”) Derivatives from CO2 and H2—Carbon Sources for Subsequent Biological Cell Evolution and Life’s Origin

Co-reporter:George A. OlahThomas Mathew, G. K. Surya Prakash

Journal of the American Chemical Society 2016 Volume 139(Issue 2) pp:566-570

Publication Date(Web):December 16, 2016

DOI:10.1021/jacs.6b10230

Formation of methanol and hydrocarbon derivatives from CO2 and H2, their simplest molecular building blocks, under biocompatible conditions is proposed. Alternate panspermia of similar extraterrestrially formed and observed hydrocarbons to earth is also discussed. The simple molecular building blocks derived from CO2 and H2 are carbon sources in the initial stage of biological evolution of cells leading to life’s origin.

Relevance and Significance of Extraterrestrial Abiological Hydrocarbon Chemistry

Co-reporter:George A. Olah; Thomas Mathew;G. K. Surya Prakash

Journal of the American Chemical Society 2016 Volume 138(Issue 22) pp:6905-6911

Publication Date(Web):April 5, 2016

DOI:10.1021/jacs.6b03136

Astrophysical observations show similarity of observed abiological “organics”—i.e., hydrocarbons, their derivatives, and ions (carbocations and carbanions)—with studied terrestrial chemistry. Their formation pathways, their related extraterrestrial hydrocarbon chemistry originating from carbon and other elements after the Big Bang, their parent hydrocarbon and derivative (methane and methanol, respectively), and transportation of derived building blocks of life by meteorites or comets to planet Earth are discussed in this Perspective. Their subsequent evolution on Earth under favorable “Goldilocks” conditions led to more complex molecules and biological systems, and eventually to humans. The relevance and significance of extraterrestrial hydrocarbon chemistry to the limits of science in relation to the physical aspects of evolution on our planet Earth are also discussed.

Iridium-Catalyzed Continuous Hydrogen Generation from Formic Acid and Its Subsequent Utilization in a Fuel Cell: Toward a Carbon Neutral Chemical Energy Storage

Co-reporter:Miklos Czaun, Jotheeswari Kothandaraman, Alain Goeppert, Bo Yang, Samuel Greenberg, Robert B. May, George A. Olah, and G. K. Surya Prakash

ACS Catalysis 2016 Volume 6(Issue 11) pp:7475

Publication Date(Web):September 27, 2016

DOI:10.1021/acscatal.6b01605

This study represents a notable step toward a potentially carbon neutral energy storage solution based on formic acid as a hydrogen/energy carrier. A catalytic system derived from IrCl3 and 1,3-bis(2′-pyridyl-imino)-isoindoline (IndH) in the presence of aqueous sodium formate showed high selectivity and robustness for hydrogen generation from formic acid (FA) at 90–100 °C under both high and moderate pressure conditions suppressing the formation of CO impurity. Being a solid substance, the catalyst can be recovered by a simple filtration, if necessary. Furthermore, addition of neat formic acid is sufficient to reuse the catalyst and maintain a constant flow of H2 and CO2 mixture and the stable performance of a coupled fuel cell. The easy to recycle catalyst did not show any loss of activity after 20 days of continuous use, and similar activity was observed even a year after the original preparation. The reactor for formic acid decomposition provided a one to one ratio of a H2/CO2 mixture that was coupled to a hydrogen/air proton exchange membrane (PEM) fuel cell to demonstrate a stable and continuous conversion of chemical energy to electricity. This integrated system embodies the first example of an indirect formic acid fuel cell, which can function, without the requirement of applying inert conditions and feed gas purification, for extended periods of time.Keywords: energy storage; formic acid decomposition; hydrogen generation; indirect formic acid fuel cell; iridium chloride

Conversion of CO2 from Air into Methanol Using a Polyamine and a Homogeneous Ruthenium Catalyst

Co-reporter:Jotheeswari Kothandaraman; Alain Goeppert; Miklos Czaun; George A. Olah;G. K. Surya Prakash

Journal of the American Chemical Society 2015 Volume 138(Issue 3) pp:778-781

Publication Date(Web):December 29, 2015

DOI:10.1021/jacs.5b12354

A highly efficient homogeneous catalyst system for the production of CH3OH from CO2 using pentaethylenehexamine and Ru-Macho-BH (1) at 125–165 °C in an ethereal solvent has been developed (initial turnover frequency = 70 h–1 at 145 °C). Ease of separation of CH3OH is demonstrated by simple distillation from the reaction mixture. The robustness of the catalytic system was shown by recycling the catalyst over five runs without significant loss of activity (turnover number > 2000). Various sources of CO2 can be used for this reaction including air, despite its low CO2 concentration (400 ppm). For the first time, we have demonstrated that CO2 captured from air can be directly converted to CH3OH in 79% yield using a homogeneous catalytic system.

Single Step Bi-reforming and Oxidative Bi-reforming of Methane (Natural Gas) with Steam and Carbon Dioxide to Metgas (CO-2H2) for Methanol Synthesis: Self-Sufficient Effective and Exclusive Oxygenation of Methane to Methanol with Oxygen

Co-reporter:George A. Olah; Alain Goeppert; Miklos Czaun; Thomas Mathew; Robert B. May;G. K. Surya Prakash

Journal of the American Chemical Society 2015 Volume 137(Issue 27) pp:8720-8729

Publication Date(Web):June 18, 2015

DOI:10.1021/jacs.5b02029

Catalysts based on suitable metal oxide supports, such as NiO/MgO and CoO/MgO, were shown to be active for single step bi-reforming, the combined steam and dry reforming of methane or natural gas with H2O and CO2 exclusively to metgas (CO-2H2) for efficient methanol synthesis. Reactions were carried out in a tubular flow reactor under pressures up to 42 bar at 830–910 °C. Using a CH4 to steam to CO2 ratio of ∼3:2:1 in the gas feed, the H2/CO ratio of 2:1 was achieved, which is desired for subsequent methanol synthesis. The needed 2/1 steam/CO2 feed ratio together with the reaction heat for the endothermic bi-reforming can be conveniently obtained by the complete combustion of a quarter part of the overall used methane (natural gas) with oxygen of the air (oxidative bi-reforming). Complete combustion of a part of methane followed by bi-reforming leads to the production of metgas (H2/CO in 2:1 mol ratio) for self-sufficient exclusive methanol synthesis. The long sought after but elusive efficient and selective oxygenation of methane to methanol is thus achieved in an effective and economic way without any oxidation byproduct formation according to CH4 + 1/2O2 → CH3OH.

Applicability of linear polyethylenimine supported on nano-silica for the adsorption of CO2 from various sources including dry air

Co-reporter:Hang Zhang, Alain Goeppert, G. K. Surya Prakash and George Olah

RSC Advances 2015 vol. 5(Issue 65) pp:52550-52562

Publication Date(Web):05 Jun 2015

DOI:10.1039/C5RA05428A

Adsorbents based on linear polyethylenimines (LPEIs) supported on fumed silica were prepared and studied for the reversible adsorption of CO2 under mild conditions from various gas mixtures, including dry air with a CO2 concentration of only 400 ppm. While the adsorption kinetics were similar between linear and branched PEI impregnated on fumed silica, the desorption rate was noticeably faster on linear PEI, which is advantageous for fast adsorption/desorption cycling. The enthalpy of CO2 adsorption was also lower on LPEI based adsorbents (−43 to −53 kJ mol−1 CO2). Desorption of the adsorbed CO2 occurred rapidly at relatively low temperatures (50 to 100 °C). The adsorption/desorption process can be repeated for more than one hundred cycles with no noticeable decrease in adsorption capacity even under humid conditions. The stability of the adsorbents under CO2, air, and N2 was also investigated.

Recycling of carbon dioxide to methanol and derived products – closing the loop

Co-reporter:Alain Goeppert, Miklos Czaun, John-Paul Jones, G. K. Surya Prakash and George A. Olah

Chemical Society Reviews 2014 vol. 43(Issue 23) pp:7995-8048

Publication Date(Web):17 Jun 2014

DOI:10.1039/C4CS00122B

Starting with coal, followed by petroleum oil and natural gas, the utilization of fossil fuels has allowed the fast and unprecedented development of human society. However, the burning of these resources in ever increasing pace is accompanied by large amounts of anthropogenic CO2 emissions, which are outpacing the natural carbon cycle, causing adverse global environmental changes, the full extent of which is still unclear. Even through fossil fuels are still abundant, they are nevertheless limited and will, in time, be depleted. Chemical recycling of CO2 to renewable fuels and materials, primarily methanol, offers a powerful alternative to tackle both issues, that is, global climate change and fossil fuel depletion. The energy needed for the reduction of CO2 can come from any renewable energy source such as solar and wind. Methanol, the simplest C1 liquid product that can be easily obtained from any carbon source, including biomass and CO2, has been proposed as a key component of such an anthropogenic carbon cycle in the framework of a “Methanol Economy”. Methanol itself is an excellent fuel for internal combustion engines, fuel cells, stoves, etc. It's dehydration product, dimethyl ether, is a diesel fuel and liquefied petroleum gas (LPG) substitute. Furthermore, methanol can be transformed to ethylene, propylene and most of the petrochemical products currently obtained from fossil fuels. The conversion of CO2 to methanol is discussed in detail in this review.

Formic Acid As a Hydrogen Storage Medium: Ruthenium-Catalyzed Generation of Hydrogen from Formic Acid in Emulsions

Co-reporter:Miklos Czaun, Alain Goeppert, Jotheeswari Kothandaraman, Robert B. May, Ralf Haiges, G. K. Surya Prakash, and George A. Olah

ACS Catalysis 2014 Volume 4(Issue 1) pp:311

Publication Date(Web):December 4, 2013

DOI:10.1021/cs4007974

Formic acid is decomposed to H2 and CO2 in the presence of RuCl3 and triphenylphosphines in an emulsion. In situ formed ruthenium carbonyls, such as [Ru(HCO2)2(CO)2(PPh3)2] (1), [Ru(CO)3(PPh3)2] (2), and [Ru2(HCO2)2(CO)4(PPh3)2] (3), and a large cluster, involving a Ru12 core, were identified and structurally characterized from the reaction mixtures. The catalytic activity of the mono and binuclear complexes was also investigated and it was found that [Ru2(HCO2)2(CO)4(PPh3)2] (3) shows high stability even at elevated temperatures and pressures and its activity is 1 order of magnitude lower than those measured for the mononuclear complexes. It was also attempted to use [Ru(HCO2)2(CO)2(PPh3)2] (1) as a catalyst for the hydrogenation of CO2 to formic acid under neutral conditions. Although the reduction of CO2 did not take place, the conversion of [Ru(HCO2)2(CO)2(PPh3)2] (1) to an unexpected carbonate, [Ru(CO3)(CO)2(PPh3)2]·H2O was observed.Keywords: emulsion; formic acid decomposition; homogeneous catalyst; hydrogen storage; ruthenium chloride

CO2 capture on easily regenerable hybrid adsorbents based on polyamines and mesocellular silica foam. Effect of pore volume of the support and polyamine molecular weight

Co-reporter:Hang Zhang, Alain Goeppert, Miklos Czaun, G. K. Surya Prakash and George A. Olah

RSC Advances 2014 vol. 4(Issue 37) pp:19403-19417

Publication Date(Web):09 Apr 2014

DOI:10.1039/C4RA02145B

Mesocellular foams (MCFs) with a wide range of pore volumes and pore sizes were prepared by varying a number of synthesis parameters such as ammonium fluoride concentration, effect of swelling agent trimethylbenzene (TMB), equilibration time and calcination heating rate. The obtained MCFs with pore volumes from 0.98 cm3 g−1 to 4.17 cm3 g−1 were impregnated with polyethylenimine (PEI) having molecular weights of 800 g mol−1 to 25000 g mol−1. These organic/inorganic hybrid materials with PEI loadings of 50 to 83% were tested for CO2 adsorption capacity, kinetics, stability and regenerability. Increasing pore volume and size in MCFs allowed the loading of higher amounts of PEI and a better distribution of PEI in the pores. Access to the active amino sites by CO2 was consequently facilitated. Adsorption of up to 6 mmol CO2 per g adsorbent (265 mg g−1) was obtained at 85 °C with the adsorbent containing PEI with a molecular weight of 800 g mol−1 loaded on the support with the highest pore volume. Contrary to expectation, the adsorbents based on PEI with the highest molecular weight had faster desorption kinetics than the ones loaded with lower molecular weight PEIs. On the other hand the CO2 adsorption kinetics for a given concentration were very similar for all PEIs, regardless of molecular weights. The adsorption capacity of the adsorbents did not decrease over 100 adsorption/desorption cycles at 75 °C. The CO2 adsorption results obtained here were in the top tier compared to the ones reported in the literature. Preparation of PEI based adsorbents clearly benefited from the utilization of supports with larger pore volume and diameter which in turn led to significantly improved CO2 adsorption characteristics.

Easily Regenerable Solid Adsorbents Based on Polyamines for Carbon Dioxide Capture from the Air

Co-reporter:Dr. Alain Goeppert;Hang Zhang;Dr. Miklos Czaun;Robert B. May; G. K. Surya Prakash; George A. Olah; S. R. Narayanan

ChemSusChem 2014 Volume 7( Issue 5) pp:1386-1397

Publication Date(Web):

DOI:10.1002/cssc.201301114

Abstract

Adsorbents prepared easily by impregnation of fumed silica with polyethylenimine (PEI) are promising candidates for the capture of CO₂ directly from the air. These inexpensive adsorbents have high CO₂ adsorption capacity at ambient temperature and can be regenerated in repeated cycles under mild conditions. Despite the very low CO₂ concentration, they are able to scrub efficiently all CO₂ out of the air in the initial hours of the experiments. The influence of parameters such as PEI loading, adsorption and desorption temperature, particle size, and PEI molecular weight on the adsorption behavior were investigated. The mild regeneration temperatures required could allow the use of waste heat available in many industrial processes as well as solar heat. CO₂ adsorption from the air has a number of applications. Removal of CO₂ from a closed environment, such as a submarine or space vehicles, is essential for life support. The supply of CO₂-free air is also critical for alkaline fuel cells and batteries. Direct air capture of CO₂ could also help mitigate the rising concerns about atmospheric CO₂ concentration and associated climatic changes, while, at the same time, provide the first step for an anthropogenic carbon cycle.

Self-Sufficient and Exclusive Oxygenation of Methane and Its Source Materials with Oxygen to Methanol via Metgas Using Oxidative Bi-reforming

Co-reporter:George A. Olah ; G. K. Surya Prakash ; Alain Goeppert ; Miklos Czaun ;Thomas Mathew

Journal of the American Chemical Society 2013 Volume 135(Issue 27) pp:10030-10031

Publication Date(Web):June 24, 2013

DOI:10.1021/ja405439c

A combination of complete methane combustion with oxygen of the air coupled with bi-reforming leads to the production of metgas (H2/CO in 2:1 mole ratio) for exclusive methanol synthesis. The newly developed oxidative bi-reforming allows direct oxygenation of methane to methanol in an overall economic and energetically efficient process, leaving very little, if any, carbon footprint or byproducts.

Study of the fluoro- and chlorodimethylbutyl cations

Co-reporter:Golam Rasul;G. K. Surya Prakash

PNAS 2013 Volume 110 (Issue 21 ) pp:8427-8430

Publication Date(Web):2013-05-21

DOI:10.1073/pnas.1306252110

A comparative study of the 2,3-dimethyl-3-fluoro-2-butyl cation and its chloro analog was carried out by the ab initio/GIAO-CCSD(T) (gauge invariant atomic orbital-coupled cluster with single, double, and perturbative triple excitation) method. The structures and 13C NMR chemical shifts of the cations were calculated at the GIAO-CCSD(T)/tzp/dz//MP2/cc-pVTZ level. Bridged fluoronium ion 1, carbenium ion 2, and fluorocarbenium ion 3 were found to be minima on the potential energy surface. Bridged fluoronium ion 1, although a minimum on the potential energy surface, is 12.8 kcal/mol less stable than the open chain fluorobutyl cation 3. In contrast to the fluorinated ion, bridged chloronium ion 5 was found to be the lowest energy minimum being 10.6 kcal/mol more stable than ion 6 and 7.4 kcal/mol more stable than ion 7.

Comparative Study of Alkane Dications (Protonated Alkyl Cations, CnH2n+22+) and Their Isoelectronic Boron Cation Analogues

Co-reporter:Golam Rasul, G. K. Surya Prakash, and George A. Olah

The Journal of Organic Chemistry 2013 Volume 78(Issue 5) pp:1747-1752

Publication Date(Web):June 25, 2012

DOI:10.1021/jo300845a

Comparative study of the superelectrophilic alkane dications (CnH2n+22+, n = 1–5) and their isoelectronic boron cation analogues was carried out using the ab initio method at the MP2/cc-pVTZ level. The structure, bonding, and relative stability of doubly charged alkane dications and monocharged boron cation analogues are discussed. These studies contribute to our general understanding of the superelectrophilic activation of alkyl cations as well as the electrophilic reactivity of C–H and C–C single bonds.

The Role of Catalysis in Replacing Oil by Renewable Methanol Using Carbon dioxide Capture and Recycling (CCR)

Co-reporter:George A. Olah

Catalysis Letters 2013 Volume 143( Issue 10) pp:983-987

Publication Date(Web):2013 October

DOI:10.1007/s10562-013-1096-1

Fossil fuels (coal, oil, gas) are nature’s major gift to humankind. Use of coal followed by petroleum oil and natural gas since the dawn of the industrial revolution in the eighteenth century brought us into a modern and increasingly technologically adept society. Limited resources, primarily depleting petroleum oil reserves and increasing world population and its demand for better standard of living, has already led to the end of cheap petroleum oil. Despite new oil discoveries, better technology, savings, efficient use etc., we must in the following decades wean ourselves out of our dependence on oil. Synthetic oil and hydrocarbons derived from coal and natural gas based on Fischer–Tropsch syngas chemistry have been at times used since the 1920s but the processes are costly, complex and limited. I have with my colleagues proposed and developed a new “Methanol Economy” approach based on metgas (CO–2H2) to methanol via bi-reforming or oxidative bi-reforming of shale or natural gas as well as carbon dioxide capture and recycling. Methanol can serve as a fuel and feed-stock to replace petroleum oil. Heterogeneous catalysis is playing key role in this fast developing field, which serves to achieve the quest for petroleum oil independence, one of the major challenges of our time. The scope and progress toward renewable methanol chemistry from the laboratory to practical industrial use are discussed.

Air as the renewable carbon source of the future: an overview of CO2 capture from the atmosphere

Co-reporter:Alain Goeppert, Miklos Czaun, G. K. Surya Prakash and George A. Olah

Energy & Environmental Science 2012 vol. 5(Issue 7) pp:7833-7853

Publication Date(Web):01 May 2012

DOI:10.1039/C2EE21586A

The burning of our diminishing fossil fuel reserves is accompanied by a large anthropogenic CO2 release, which is outpacing nature's CO2 recycling capability, causing significant environmental harm. Much is being done to avert this crisis including more efficient technology for usage, savings and replacing carbon fuels with alternatives whenever feasible. The capture of CO2 followed by sequestration (CCS) into geologic formation or under the seas has also been proposed and in some cases implemented. Carbon capture and recycling (CCR) to fuels and materials is another promising approach. At first, capturing carbon dioxide from concentrated sources such as fossil fuel burning power plants, industrial plants and natural sources might be the most practical. However, the capture of CO2 from the atmosphere is also technically feasible despite its low concentration (∼390 ppm) and presents even some benefits compared to point source CO2 capture. The present article reviews methods developed for the capture of CO2 directly from the air as well as their advantages and drawbacks. While strong bases such as sodium hydroxide and potassium hydroxide could be used, their regeneration is energy intensive, requiring high temperatures. Amines either physically or chemically immobilized on solid supports require much lower temperatures for their regeneration and are therefore promising candidates.

Bi-reforming of Methane from Any Source with Steam and Carbon Dioxide Exclusively to Metgas (CO–2H2) for Methanol and Hydrocarbon Synthesis

Co-reporter:George A. Olah ; Alain Goeppert ; Miklos Czaun ;G. K. Surya Prakash

Journal of the American Chemical Society 2012 Volume 135(Issue 2) pp:648-650

Publication Date(Web):December 20, 2012

DOI:10.1021/ja311796n

A catalyst based on nickel oxide on magnesium oxide (NiO/MgO) thermally activated under hydrogen is effective for the bi-reforming with steam and CO2 (combined steam and dry reforming) of methane as well as natural gas in a tubular flow reactor at elevated pressures (5–30 atm) and temperatures (800–950 °C). By adjusting the CO2-to-steam ratio in the gas feed, the H2/CO ratio in the produced syn-gas could be easily adjusted in a single step to the desired value of 2 for methanol and hydrocarbon synthesis.

Octahydriodo diborane (B2H8) and its protonated cations containing five-, six-, and seven-coordinate boron atoms

Co-reporter:Golam Rasul;G. K. Surya Prakash

PNAS 2012 Volume 109 (Issue 18 ) pp:

Publication Date(Web):2012-05-01

DOI:10.1073/pnas.1204184109

Structures of octahydriodo diborane (B2H8) 1 and its protonated 3, diprotonated 5, triprotonated 6, and tetraprotonated 7 ions were found to be calculationally viable minima at the MP2/cc-pVTZ level of theory. Each structure contains two-electron three-center (2e-3c) bonds. The protonation of 1 to form 3 was found to be strongly exothermic by 176.0 kcal/mol. Subsequent protonation of 3 to form 5 was also found to be exothermic by 28.4 kcal/mol. Further protonation of 5 to form 6 was, however, computed to be endothermic by 122.0 kcal/mol whereas protonation of 6 to form 7 was again highly endothermic by 238.8 kcal/mol. Deprotonation barriers of the ions were also computed.

Conformational Study of 9-Dehydro-9-Trifluoromethyl Cinchona Alkaloids via 19F NMR Spectroscopy: Emergence of Trifluoromethyl Moiety as a Conformational Stabilizer and a Probe

Co-reporter:G. K. Surya Prakash ; Fang Wang ; Chuanfa Ni ; Jingguo Shen ; Ralf Haiges ; Andrei K. Yudin ; Thomas Mathew

Journal of the American Chemical Society 2011 Volume 133(Issue 26) pp:9992-9995

Publication Date(Web):June 7, 2011

DOI:10.1021/ja202373d

The trifluoromethyl substituent has been incorporated into quinidine as a conformational stabilizer and a probe to provide straightforward insight into the conformational behavior of cinchona alkaloids. By significantly decreasing the rotation rate of the quinoline–carbinol bond, the relatively bulky CF3 group enables the NMR signals of the syn and anti conformers to be differentiated at room temperature. In addition to the stabilizing effect, the introduction of the fluorinated moiety also facilitates the application of 19F NMR spectroscopy, thereby allowing conformational studies under various conditions without the use of deuterated solvents.

Carbon Dioxide Capture from the Air Using a Polyamine Based Regenerable Solid Adsorbent

Co-reporter:Alain Goeppert ; Miklos Czaun ; Robert B. May ; G. K. Surya Prakash ; George A. Olah ;S. R. Narayanan

Journal of the American Chemical Society 2011 Volume 133(Issue 50) pp:20164-20167

Publication Date(Web):November 21, 2011

DOI:10.1021/ja2100005

Easy to prepare solid materials based on fumed silica impregnated with polyethylenimine (PEI) were found to be superior adsorbents for the capture of carbon dioxide directly from air. During the initial hours of the experiments, these adsorbents effectively scrubbed all the CO2 from the air despite its very low concentration. The effect of moisture on the adsorption characteristics and capacity was studied at room temperature. Regenerative ability was also determined in a short series of adsorption/desorption cycles.

Comparative study of the hypercoordinate carbonium ions and their boron analogs: A challenge for spectroscopists

Co-reporter:Golam Rasul, G.K. Surya Prakash, George A. Olah

Chemical Physics Letters 2011 Volume 517(1–3) pp:1-8

Publication Date(Web):28 November 2011

DOI:10.1016/j.cplett.2011.10.020

Abstract

Theoretical and related experimental studies have shown that carbon can extend its bonding from Kekule’s tetravalent methane to five, six or seven coordinated protonated methanes, i.e., CH₅⁺, CH₆²⁺ and CH₇³⁺ and their analogs. Ab initio calculations indicate that higher coordinated, highly charged carbonium ions could be viable species despite the substantial charge–charge repulsion. Structure and bonding of such carbonium ions and the isoelectronic boron analogs were studied and are discussed. These contribute to our general understanding of the electrophilic reactivity of C–H and C–C single bonds.

On the Nature of CHFC Interactions in Hindered CF3C(sp3) Bond Rotations

Co-reporter:Dr. G. K. Surya Prakash;Fang Wang;Dr. Martin Rahm;Dr. Jingguo Shen;Dr. Chuanfa Ni;Dr. Ralf Haiges ;Dr. George A. Olah

Angewandte Chemie International Edition 2011 Volume 50( Issue 49) pp:11761-11764

Publication Date(Web):

DOI:10.1002/anie.201105288

From Difluoromethyl 2-Pyridyl Sulfone to Difluorinated Sulfonates: A Protocol for Nucleophilic Difluoro(sulfonato)methylation

Co-reporter:Dr. G. K. Surya Prakash;Dr. Chuanfa Ni;Fang Wang;Dr. Jinbo Hu;Dr. George A. Olah

Angewandte Chemie International Edition 2011 Volume 50( Issue 11) pp:2559-2563

Publication Date(Web):

DOI:10.1002/anie.201007594

Hydrogen Generation from Formic Acid Decomposition by Ruthenium Carbonyl Complexes. Tetraruthenium Dodecacarbonyl Tetrahydride as an Active Intermediate

Co-reporter:Dr. Miklos Czaun;Dr. Alain Goeppert;Robert May;Dr. Ralf Haiges;Dr. G. K. Surya Prakash;Dr. George A. Olah

ChemSusChem 2011 Volume 4( Issue 9) pp:1241-1248

Publication Date(Web):

DOI:10.1002/cssc.201000446

Abstract

The present Minireview covers the formation and the structural characterization of noble metal carbonyl and hydrido carbonyl complexes, with particular emphasis on ruthenium complexes using formic acid as a carbonyl and hydride source. The catalytic activity of these organometallic compounds for the decarboxylation of formic acid, a potential hydrogen storage material, is also reviewed. In addition, the first preparation of [Ru₄(CO)₁₂H₄] from RuCl₃ and formic acid as well as the catalytic activity of [Ru₄(CO)₁₂H₄] for the decomposition of formic acid to hydrogen and carbon dioxide are presented.

Nanostructured silica as a support for regenerable high-capacity organoamine-based CO2 sorbents

Co-reporter:Alain Goeppert, Sergio Meth, G. K. Surya Prakash and George A. Olah

Energy & Environmental Science 2010 vol. 3(Issue 12) pp:1949-1960

Publication Date(Web):05 Oct 2010

DOI:10.1039/C0EE00136H

Nanostructured precipitated and fumed silica (nanosilica) were found to be superior supports for the immobilization of various organoamines. The easily prepared solids were found to be regenerable and effective CO2 absorbents at moderate temperatures from room temperature up to 100 °C. Supported polyethylenimines (PEIs), especially branched low-molecular-weight (LMW, Mwca. 800) and high-molecular-weight (HMW, Mwca. 25000) PEIs were particularly suitable as CO2 absorbents. Amines with lower molecular weights and lower boiling points such as pentaethylenehexamine (PEH), tetraethylenepentamine (TEP), monoethanolamine (MEA) and diethanolamine (DEA) showed sorbent leaching from the solid absorbents. The addition of poly(ethylene glycol) was found to significantly enhance the subsequently needed desorption of CO2 from PEI-based solid absorbents. In the preparation of CO2 absorbents, the particle size of the nanosilica was found to be of advantage compared to other solid supports having similar or higher surface area but larger particle size.

Synthesis and biological evaluation of fluorinated deoxynucleotide analogs based on bis-(difluoromethylene)triphosphoric acid

Co-reporter:Charles E. McKenna;Mikhail Zibinsky;Boris A. Kashemirov;G. K. Surya Prakash;Thomas G. Upton;Keriann Oertell;Myron F. Goodman;Vinod K. Batra;Lars C. Pedersen;William A. Beard;David D. Shock;Samuel H. Wilson

PNAS 2010 Volume 107 (Issue 36 ) pp:15693-15698

Publication Date(Web):2010-09-07

DOI:10.1073/pnas.1007430107

It is difficult to overestimate the importance of nucleoside triphosphates in cellular chemistry: They are the building blocks for DNA and RNA and important sources of energy. Modifications of biologically important organic molecules with fluorine are of great interest to chemists and biologists because the size and electronegativity of the fluorine atom can be used to make defined structural alterations to biologically important molecules. Although the concept of nonhydrolyzable nucleotides has been around for some time, the progress in the area of modified triphosphates was limited by the lack of synthetic methods allowing to access bisCF2-substituted nucleotide analogs—one of the most interesting classes of nonhydrolyzable nucleotides. These compounds have “correct” polarity and the smallest possible steric perturbation compared to natural nucleotides. No other known nucleotides have these advantages, making bisCF2-substituted analogs unique. Herein, we report a concise route for the preparation of hitherto unknown highly acidic and polybasic bis(difluoromethylene)triphosphoric acid 1 using a phosphorous(III)/phosphorous(V) interconversion approach. The analog 1 compared to triphosphoric acid is enzymatically nonhydrolyzable due to substitution of two bridging oxygen atoms with CF2 groups, maintaining minimal perturbations in steric bulkiness and overall polarity of the triphosphate polyanion. The fluorinated triphosphoric acid 1 was used for the preparation of the corresponding fluorinated deoxynucleotides (dNTPs). One of these dNTP analogs (dT) was demonstrated to fit into DNA polymerase beta (DNA pol β) binding pocket by obtaining a 2.5 Å resolution crystal structure of a ternary complex with the enzyme. Unexpected dominating effect of triphosphate/Mg2+ interaction over Watson–Crick hydrogen bonding was found and discussed.

Vicinal dihalonium ions: diprotonated and dimethylated chlorine [, ] and bromine [, ] dications

Co-reporter:George A. Olah;G. K. Surya Prakash;Golam Rasul

PNAS 2010 107 (15 ) pp:6716-6720

Publication Date(Web):2010-04-13

DOI:10.1073/pnas.1001603107

High level ab initio calculations at the MP2/cc-pVTZ, CCSD(T)/cc-pVTZ, and CASSCF(6,6)/cc-pVTZ levels were performed to investigate geometries and energies of superelectrophilic diprotonated, and dimethylated molecular chlorine () and bromine () dications. Diprotonated chlorine and diprotonated bromine dications 3a and 6a, respectively, were found to be lowest energy minima. The isomeric dications, 3b and 6b, are also minima on the potential energy surfaces but they are significantly less stable than the structures 3a and 6a by 33.6 and 30.9 kcal/mol, respectively. On the basis of computed G2 energies, proton affinities and related thermodynamic parameters were also calculated. Dications 3a and 6a have substantial kinetic barriers for deprotonation. Their homolytic dissociation are however facile. Dimethylated molecular chlorine and bromine dications 3g and 6g, respectively, were also found to be global energy minima. These vicinal dihalonium or the corresponding protosolvated species are expected to form either in the superacidic media or in the gas phase.

α-Fluoro-α-nitro(phenylsulfonyl)methane as a fluoromethyl pronucleophile: Efficient stereoselective Michael addition to chalcones

Co-reporter:G. K. Surya Prakash;Fang Wang;Timothy Stewart;Thomas Mathew

PNAS 2009 106 (11 ) pp:4090-4094

Publication Date(Web):2009-03-17

DOI:10.1073/pnas.0900179106

Highly efficient stereoselective 1,4-addition of racemic α-fluoro-α-nitro(phenylsulfonyl)methane (FNSM) as a fluoromethyl pronucleophile to α,β-unsaturated ketones using a wide range of chiral organobifunctional catalysts under moderate conditions in the absence of an additional base has been achieved. A series of catalysts was screened for the enantioselective addition of FNSM to chalcones and the catalysts CN I, CD I, QN I-IV, and QD I were found to enable this reaction, successfully providing exclusive 1,4-addition products stereoselectively in high yields (conversion, diastereomeric ratio, and enantiomeric excess). Studies involving a model reaction and systematic analysis of the absolute configuration support the suggested mechanism.

A Persistent -Fluorocarbanion and Its Analogues: Preparation, Characterization, and Computational Study

Co-reporter:G.K.Surya Prakash Dr.;Fang Wang;Nan Shao;Thomas Mathew Dr.;Golam Rasul Dr.;Ralf Haiges Dr.;Timothy Stewart ;GeorgeA. Olah Dr.

Angewandte Chemie International Edition 2009 Volume 48( Issue 29) pp:5358-5362

Publication Date(Web):

DOI:10.1002/anie.200901414

Calculational Study of Fluoroammonium and Related Cations and Dications

Co-reporter:GeorgeA. Olah Dr.;G.K.Surya Prakash Dr. ;Golam Rasul Dr.

Chemistry - A European Journal 2009 Volume 15( Issue 34) pp:8443-8448

Publication Date(Web):

DOI:10.1002/chem.200900335

Abstract

Structures as well as ¹⁵N and ¹⁹F NMR chemical shifts of a series of fluoroammonium ions were studied by ab initio/GIAO-SCF, GIAO-MP2 and GIAO-CCSD(T) methods. Calculated ¹⁵N and ¹⁹F NMR chemical shifts correlate well with the experimental data. The relative stabilities as well as the charge of the central nitrogen atom of fluoro-substituted tetrahedral ammonium ions were found to increase linearly with the increasing number of fluorine substituents due to their strong electron-withdrawing inductive effect. Similarly the magnitude of ¹⁵N NMR chemical shifts also increase linearly with the increasing number of fluorine substituents in accord with the strong deshielding effect of fluorine. Structures as well as ¹⁵N and ¹⁹F NMR chemical shifts of yet experimentally unknown fluoroammonium dications were also computed.

Protonated tert-pentyl dication (C5H122+, isopentane dication)

Co-reporter:George A. Olah, G. K. Surya Prakash and Golam Rasul

Dalton Transactions 2008 (Issue 4) pp:521-526

Publication Date(Web):07 Nov 2007

DOI:10.1039/B713188G

Structures of the tert-pentyl cation (C5H11+) and its protonated dication (C5H122+, isopentane dication) were studied using ab initio methods at the MP2/cc-pVTZ level. Both C–C and C–H hyperconjugatively stabilized structures 1 and 2, respectively, were found to be minima on the potential energy surface (PES) of the tert-pentyl cation. Structure 1 was computed to be about as stable as structure 2 (slightly more stable by 0.5 kcal mol–1). Inter-conversion between 1 and 2 through transition state 3 has a kinetic barrier of only 1.5 kcal mol–1. The C–H protonated form (H3C)2C+CH2CH4+4 was found to be the global minimum for the protonated tert-pentyl dication. Charges and 13C NMR chemical shifts of the dication 4 were calculated and compared to those of monocation 1 to study the effect of the additional charge in the dication.

Stereoselective Monofluoromethylation of Primary and Secondary Alcohols by Using a Fluorocarbon Nucleophile in a Mitsunobu Reaction

Co-reporter:G. K. Surya Prakash Dr.;Sujith Chacko;Steevens Alconcel;Timothy Stewart;Thomas Mathew Dr.;George A. Olah Dr.

Angewandte Chemie International Edition 2007 Volume 46(Issue 26) pp:

Publication Date(Web):23 MAY 2007

DOI:10.1002/anie.200700834

OH is exchanged: An efficient Mitsunobu reaction that uses a fluorinated carbon pronucleophile for the facile synthesis of monofluoromethyl derivatives of alcohols is reported (see scheme; DIAD=diisopropyl azodicarboxylate). This reaction can be performed under mild conditions and is highly feasible for primary, secondary, allylic, benzylic, and alicyclic alcohols. Excellent enantiospecificity is observed for chiral alcohols.

Gallium (III) triflate catalyzed efficient Strecker reaction of ketones and their fluorinated analogs

Co-reporter:G. K. Surya Prakash;Thomas Mathew;Chiradeep Panja;Steevens Alconcel;Habiba Vaghoo;Clement Do;

Proceedings of the National Academy of Sciences 2007 104(10) pp:3703-3706

Publication Date(Web):February 28, 2007

DOI:10.1073/pnas.0611316104

The synthesis of α-aminonitriles and their fluorinated analogs has been carried out in high yield and purity by the Strecker reaction from the corresponding ketones and amines with trimethylsilyl cyanide using gallium triflate in dichloromethane. Monofluoro-, difluro-, or trifluoromethyl groups can be incorporated into the α-aminonitrile product by varying the nature of the fluorinated ketones. Study with various fluorinated and nonfluorinated ketones reveals that the choice of proper catalyst and the solvent system (suitable metal triflates as a catalyst and dichloromethane as a solvent) plays the key role in the direct Strecker reactions of ketones.

PVP-SO2 complex as a solid mild acid catalyst for efficient one pot, three component, Strecker synthesis of α−aminonitriles

Co-reporter:George A. Olah;Thomas Mathew;Chiradeep Panja;Kiah Smith

Catalysis Letters 2007 Volume 114( Issue 1-2) pp:1-7

Publication Date(Web):2007 March

DOI:10.1007/s10562-007-9031-y

Solid poly(4-vinylpyridine)-SO2 complex was prepared and used as a mild solid acid catalyst for simple and efficient three component Strecker synthesis of α-aminonitriles in high yield and purity.

Stereoselective Monofluoromethylation of Primary and Secondary Alcohols by Using a Fluorocarbon Nucleophile in a Mitsunobu Reaction

Co-reporter:G. K. Surya Prakash Dr.;Sujith Chacko;Steevens Alconcel;Timothy Stewart;Thomas Mathew Dr.;George A. Olah Dr.

Angewandte Chemie 2007 Volume 119(Issue 26) pp:

Publication Date(Web):23 MAY 2007

DOI:10.1002/ange.200700834

OH wird ausgetauscht: Eine effiziente Mitsunobu-Reaktion mit einem fluorierten Kohlenstoff-Pronucleophil eröffnet ausgehend von Alkoholen einen leichten Zugang zu Monofluormethyl-Derivaten (siehe Schema, DIAD=Diisopropylazodicarboxylat). Die Reaktion verläuft unter milden Bedingungen mit primären, sekundären und alicyclischen Alkoholen sowie mit Allyl- und Benzylalkoholen. Chirale Alkohole reagieren enantiospezifisch.

Effect of carbonates/phosphates as nucleophilic catalysts in dimethylformamide for efficient cyanosilylation of aldehydes and ketones

Co-reporter:G. K. Surya Prakash;Roman Kultyshev;Vijayalakshmi Surampudi;Chiradeep Panja;Habiba Vaghoo;Thomas Mathew

PNAS 2007 Volume 104 (Issue 9 ) pp:3026-3030

Publication Date(Web):2007-02-27

DOI:10.1073/pnas.0611309104

Cyanosilylation of aldehydes and aliphatic ketones can be carried out in dimethylformamide even without the use of any catalyst. In the presence of nucleophilic catalysts such as carbonate and phosphate salts, the reaction rate is significantly enhanced.

The question of C- vs. O-silylation of ketenes: Electrophilic triethylsilylation of diphenylketene

Co-reporter:G. K. Surya Prakash;Chulsung Bae;Golam Rasul;

Proceedings of the National Academy of Sciences 2005 102(18) pp:6251-6254

Publication Date(Web):April 19, 2005

DOI:10.1073/pnas.0501813102

Electrophilic triethylsilylation of diphenylketene leads to exclusive C-silylation giving the diphenyl(triethylsilyl)acetyl cation in the solution phase even though density functional theory calculations at the B3LYP/6-311+G^* level indicate that the O-silylation of diphenylketene is preferred over C-silylation by 5.4 kcal/mol in the gas phase. On the other hand, in the case of the parent ketene, similar density functional theory calculations show that C-silylation is preferred over O-silylation by 8.2 kcal/mol.

Beyond Oil and Gas: The Methanol Economy

Co-reporter:George A. Olah Dr.

Angewandte Chemie International Edition 2005 Volume 44(Issue 18) pp:

Publication Date(Web):31 MAR 2005

DOI:10.1002/anie.200462121

Methanol, a convenient liquid fuel and raw material for synthetic hydrocarbons, offers an alternative to depleting sources of fossil fuels and can be produced, for example, by reacting H₂ with CO₂ from industrial effluents or the atmosphere—good news with regards to global-warming concerns. This Essay discusses various aspects of current and alternative energy sources, with a particular focus on the “methanol economy” (see scheme).

Jenseits von Öl und Gas: die Methanolwirtschaft

Co-reporter:George A. Olah Dr.

Angewandte Chemie 2005 Volume 117(Issue 18) pp:

Publication Date(Web):31 MAR 2005

DOI:10.1002/ange.200462121

Methanol, ein einfach zu handhabender flüssiger Brennstoff und Grundstoff für die Kohlenwasserstoffsynthese, ist eine Alternative zu den stetig abnehmenden fossilen Brennstoffen. Es kann beispielsweise durch die Umsetzung von H₂ mit CO₂ aus Industrieabgasen oder der Atmosphäre gewonnen werden – gute Nachrichten im Hinblick auf die globale Erwärmung. Dieser Essay behandelt herkömmliche und alternative Energiequellen unter besonderer Berücksichtigung der „Methanolwirtschaft“ (siehe Schema).

Fulvio Cacace (1931–2003): Structure and Mechanism in Gas-Phase Chemistry and Its Relevance to the Condensed State

Co-reporter:George A. Olah

Angewandte Chemie International Edition 2004 Volume 43(Issue 14) pp:

Publication Date(Web):24 MAR 2004

DOI:10.1002/anie.200420086

Density functional theory study of adamantanediyl dications C10H142+ and protio-adamantyl dications C10H162+

Co-reporter:Golam Rasul;G. K. Surya Prakash

PNAS 2004 Volume 101 (Issue 30 ) pp:10868-10871

Publication Date(Web):2004-07-27

DOI:10.1073/pnas.0404137101

Structures of the isomeric adamantanediyl dications C10H14 2+ and protio-1- and protio-2-adamantyl dications C10H16 2+ were investigated by using the density functional theory (DFT) method at the B3LYP/6–31G** level. Four structures, 1 b–e, were found to be minima on the potential energy surface of C10H14 2+. The 1,3-adamantanediyl dication 1b with two bridgehead tertiary carbocationic centers was found to be the most stable structure. On the potential energy surface of C10H16 2+ (protonated adamantly cation), five structures, 2 b–f, were found to be minima. Each of the structure contains a two-electron, three-center bond. The C—C protonated 1-adamantyl dication, 2f, was characterized as the most stable structure. 13C NMR chemical shifts of the structures were also calculated by using gauge-including atomic orbital-density functional theory and gauge-including atomic orbital-self-consistent field methods.

Fulvio Cacace (1931–2003): Strukturen und Mechanismen in der Gasphasenchemie und ihre Relevanz für die kondensierte Materie

Co-reporter:George A. Olah

Angewandte Chemie 2004 Volume 116(Issue 14) pp:

Publication Date(Web):24 MAR 2004

DOI:10.1002/ange.200420086

Ab initio/GIAO-MP2-calculated structures and 11B-13C NMR chemical shift relationship in hypercoordinate onium-carbonium dications and isoelectronic onium-boronium cations

Co-reporter:Golam Rasul;G. K. Surya Prakash

PNAS 2002 99 (15 ) pp:9635-9638

Publication Date(Web):2002-07-23

DOI:10.1073/pnas.142294599

The boronium–carbonium ion continuum was extended to include hypercoordinated onium-carbonium dications and the isoelectronic onium-boronium cation analogs. Structures and 13C and 11B NMR chemical shifts of the onium-carbonium dications and the corresponding isoelectronic and isostructural onium-boronium cations were calculated with the ab initio/GIAO-MP2 method. The data show a good linear correlation between 11B and 13C NMR chemical shifts, indicating that the same factors that determine the chemical shifts of the boron nuclei also govern the chemical shifts of carbon nuclei of these hypercoordinated onium ions and dications.

Organoamines-grafted on nano-sized silica for carbon dioxide capture

Co-reporter:Miklos Czaun, Alain Goeppert, Robert B. May, Drew Peltier, Hang Zhang, G.K. Surya Prakash, George A. Olah

Journal of CO2 Utilization (June 2013) Volume 1() pp:1-7

Publication Date(Web):1 June 2013

DOI:10.1016/j.jcou.2013.03.007

•Commercially available and more cost effective support has been used for the synthesis of the new adsorbents.•Amine compounds are chemically bonded to the support preventing amine leaching and minimizing their environmental and health hazard.•More cost effective regeneration step due to significantly lower heat capacity (≈0.73 J g−1 °C−1) compared with aqueous solutions.•First example of one step grafting of trimethoxysilylpropyl-polyethyleneimine onto silica for the synthesis of CO2 adsorbent materials.•Enhanced graft densities were obtained by the saturation of the silane agents with CO2 before grafting to the surface.Organoamine–inorganic hybrid adsorbent materials were synthesized by covalent immobilization of alkylaminotrimethoxysilanes and polyethyleneiminetrimethoxysilane onto fumed silica (nanosilica). The obtained silica–organic hybrid materials were characterized by thermogravimetry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) confirming the successful grafting of the amine derivatives to silica and their surface area measured using Brunauer–Emmett–Teller method (BET). The influence of reaction conditions on the graft density of organoamines was investigated and it was found that the saturation of the silane coupling agents with carbon dioxide prior to surface modification resulted in higher graft densities. Carbon dioxide uptake of the obtained hybrid materials were determined by thermogravimetric analysis at room temperature as well as higher temperatures resulting in CO2 adsorption capacities from 32.4 to 69.7 mg g−1 adsorbent.Download full-size image

Comparative ab initio/GIAO-CCSD(T) study of protonated propionaldehyde, isobutyraldehyde and pivalaldehyde cations and their superelectrophilic diprotonated dications

Co-reporter:George A. Olah, G.K. Surya Prakash, Golam Rasul

Journal of Molecular Structure (12 November 2008) Volume 890(Issues 1–3) pp:

Publication Date(Web):12 November 2008

DOI:10.1016/j.molstruc.2007.11.057

Structures of superelectrophilic diprotonated propionaldehyde (CH3CH2CHOH22+), isobutyraldehyde ((CH3)2CHCHOH22+) and pivalaldehyde ((CH3)3CCHOH22+) dications and their parent monocations were calculated using ab initio methods at the MP2/6-31G∗∗ and MP2/cc-pVTZ levels. Proton affinities of the neutral as well as monoprotonated aldehydes were calculated. Compared to proton affinities of neutral aldehydes, relative proton affinities of monoprotonated aldehydes were found to increase much more rapidly with the increase of methyl substitution. 13C NMR chemical shifts were also calculated using the GIAO-CCSD(T), GIAO-MP2 and GIAO-SCF methods. 13C NMR chemical shifts of the related tert-butyl cation ((CH3)3C+) and protonated tert-butyl dication ((CH3)2CCH42+) were computed at the same level for comparison and to explore the effect of the additional charge in dications.

Zinc catalyzed conversion of methanol–methyl iodide to hydrocarbons with increased formation of triptane

Co-reporter:Stéphane Walspurger, G.K. Surya Prakash, George A. Olah

Applied Catalysis A: General (1 March 2008) Volume 336(Issues 1–2) pp:

Publication Date(Web):1 March 2008

DOI:10.1016/j.apcata.2007.08.035

At 200 °C under autogeneous pressure, mixtures of methanol and methyl halides are converted with zinc to a mixture of hydrocarbons. The reaction of methanol and methyl iodide mixtures over zinc or zinc oxide gives 2,2,3-trimethylbutane (triptane), a desirable high-octane compound in significant selectivity. As alternative to previously known ZnI2 or ZnBr2/methanol conversion, the present protocol does not require the use of metal halide catalysts. The initial step of the mechanism of conversion methanol/methyl iodide mixtures to hydrocarbons does not involve strongly acidic species. On the basis of the obtained experimental data with both zinc and zinc oxide, which are amphoteric in nature, the intermediacy of a zinc methoxy species is considered to be the key step for the formation of hydrocarbons. The proposed formation of hydrocarbons is considered as a parallel reaction to ethylene oligomerization to aromatic hydrocarbons.At 200 °C under autogeneous pressure, mixtures of methanol and methyl halides are converted with zinc to a mixture of hydrocarbons. The reaction of methanol and methyl iodide mixtures over zinc or zinc oxide gives 2,2,3-trimethylbutane (triptane), a desirable high-octane compound in significant selectivity. The mechanism of these reactions under amphoteric conditions is discussed.

Anthropogenic Chemical Carbon Cycle for a Sustainable Future

Co-reporter:George A. Olah ; G. K. Surya Prakash ;Alain Goeppert

Journal of the American Chemical Society () pp:

Publication Date(Web):May 25, 2011

DOI:10.1021/ja202642y

Fluoroanalogs of DDT: Superacidic BF3–H2O Catalyzed Facile Synthesis of 1,1,1-Trifluoro-2,2-diarylethanes and 1,1-Difluoro-2,2-diarylethanes

Co-reporter:G. K. Surya Prakash ; Farzaneh Paknia ; Thomas Mathew ; Gzregorz Mlostoń ; Jens P. Joschek

Organic Letters () pp:

Publication Date(Web):July 12, 2011

DOI:10.1021/ol201669a

The one-pot synthesis of 1,1,1-trifluoro- and 1,1-difluoro-2,2-diarylethanes from arenes and fluorinated hemiacetals in the BF3–H2O system is described. The reaction is simple, clean, and convenient, eliminating the use of organic solvents and other expensive acid systems. BF3–H2O is economic, is easy to prepare, and offers ample acidity required for this reaction.

Recycling of carbon dioxide to methanol and derived products – closing the loop

Co-reporter:Alain Goeppert, Miklos Czaun, John-Paul Jones, G. K. Surya Prakash and George A. Olah

Chemical Society Reviews 2014 - vol. 43(Issue 23) pp:NaN8048-8048

Publication Date(Web):2014/06/17

DOI:10.1039/C4CS00122B

Protonated tert-pentyl dication (C5H122+, isopentane dication)

Co-reporter:George A. Olah, G. K. Surya Prakash and Golam Rasul

Dalton Transactions 2008(Issue 4) pp:NaN526-526

Publication Date(Web):2007/11/07

DOI:10.1039/B713188G