Hydrolytic hydrogenation of cellulose requires both functionalities of a metal and acid site. HZSM-5 has strong acid sites inside the micropores. However, those sites are not easily accessible to large molecules derived from cellulose. In this work, NaOH treatment of ZSM-5 was applied to introduce mesopores to the crystallite of ZSM-5. Characterizations showed that mesopores of 4–20 nm were successfully created on the surface of ZSM-5, and mesopore volume and total acid density (particularly Lewis acid density) increased as the severity of treatment increased. Loading of Ru on the mesoporous HZSM-5 resulted in a highly active and selective catalyst for conversion of cellulose to hexitols. The optimized hexitols yield of 39.4 % is 6 times higher than that of Ru supported on the parent HZSM-5. Model reaction studies (hydrolysis of cellobiose and hydrogenation of glucose) indicated that the enhanced acid density (particularly Lewis acid in mesopores) promotes the hydrolysis of oligosaccharides from primary depolymerization of cellulose. Furthermore, the uniform dispersion of smaller Ru nanoparticles due to the increased surface area caused by the mesopore enhanced the activity of the hydrogenation reaction. Consequently, a high yield of hexitols with reduced yield of small polyols was achieved on the optimized mesoporous Ru/HZSM-5.

We report a process of selective conversion of microcrystalline cellulose to hexitols over bi-functional Ru-supported sulfated zirconia and silica-zirconia catalysts. A 58.1% yield of hexitols and a 71.0% conversion of cellulose were achieved over Ru/SZSi(100:15)-773 catalyst at 443 K. The as-synthesized catalysts were characterized by X-ray diffraction (XRD), BET, thermogravimetric analysis and pyridine adsorption Fourier transform infrared spectroscopy (FTIR). XRD results indicated that the sulfated catalysts were pure tetragonal phase of ZrO2 when calcined at 773 K. Monoclinic zirconia appeared at the calcination temperature of 873 K, and the content of monoclinic phase increased with the elevating temperature. Compared with sulfated zirconia catalyst, sulfated silica-zirconia catalysts possessed a higher ratio of Brønsted to Lewis on the surface of catalysts, as shown from pyridine adsorption FTIR results. The reaction results indicated that the tetragonal zirconia, which is necessary for the formation of superacidity, was the active phase to cellulose conversion. The higher amounts of Brønsted acid sites can remarkably accelerate the cellulose depolymerization and promote side reactions that convert C5–C6 alcohols into the unknown soluble degradation products.

•Supported Ru on zirconia-modified SBA-15 catalyst has been prepared.•Zirconia modifier creates acid sites and improves Ru dispersion.•Mesopores of SBA-15 was preserved at Zr/Si = 0.25.•Hydrogenation of cellobiose is the first step of the conversion.•Hydrolysis of glucitol is the rate-determining step.Ru supported on zirconia-modified SBA-15 as a catalyst for selective conversion of cellobiose has been prepared and characterized using X-ray diffraction, N2 adsorption, transmission electron microscopy, and temperature programmed desorption of NH3. Coating SBA-15 with zirconia generates acid sites as well as improves Ru dispersion in the mesopore. At a Zr/Si ratio of 0.25 (∼1.4 monolayer coverage of zirconia on the SBA-15 surface), the mesoporous structure of SBA-15 was well preserved in zirconia-modified SBA-15. Increasing the amount of zirconia beyond Zr/Si = 0.5 resulted in narrowing of the mesopores and, eventually, pore blockage. Mechanistic study of cellobiose conversion on the catalyst indicates that the reaction proceeds sequentially through (a) hydrogenolysis/hydrogenation of cellobiose to 3-β-d-glucopyranosyl-d-glucitol, (b) hydrolysis to sorbitol and glucose, and (c) glucose hydrogenation to hexitols, with the hydrolysis step being the rate-determining step for hexitols formation. A complete conversion of cellobiose with a hexitols yield of 72% has been achieved at 140 °C in 1 h with the optimal Zr/Si ratio of 0.25. A comparison with the more acidic Ru/HZSM-5 catalyst demonstrated the importance of the mesopores of SBA-15 to the catalytic reactivity of Ru/Zr-SBA-15(0.25).

The coupling reaction of propylene and CO2 to form propylene carbonate (PC) was promoted by an ionic liquid (IL) covalently bound to polyethylene glycol (PEG). The supported ionic liquid, which has both acidic and basic components, proved to be an active catalyst for PC synthesis under mild conditions. The effects of different cations and anions, reaction temperature, CO2 pressure, and reaction time were investigated. It was demonstrated that the acid group in the catalyst plays an important role in the reaction. With this system, a high PC yield (95%) was achieved under mild conditions (3.0 MPa, 120°C and 4 h) without a co-solvent. In addition, the catalyst was readily recovered and reused. Based on the experimental results, a plausible mechanism for the catalyst was proposed.

Ammonium dinitramide (ADN), NH4N(NO2)2, is one of the most promising oxidizing components of future solid propellant formulations, because it is eco-friendly and more energetic and has no plume signature because there is no chlorine in its molecular structure. The hygroscopicity of the ADN crystal, which is more severe than that of ammonium perchlorate (AP), seriously affects its use. This quite different behavior is possibly associated with their structures. The X-ray single-crystal diffraction data show that vast hydrogen bonds link the ADN structure. The three-dimensional structure of ADN joined by the fourth longer hydrogen bond is an unusual two-fold three-dimensional interpropagation network structure, and the hydrogen bonds in the ADN crystal are much shorter than that in AP because of the special structure. The hydrogen bonds between ADN and water are assayed by IR spectroscopy. Differential scanning calorimetric (DSC) analysis of moisture-containing ADN and AP crystals also confirm that, because of the stronger hydrogen bond between ADN and water molecules, large amounts of bound water are present in the ADN besides some unbound water. All of this evidence suggests that the special hydrogen bonds among ADN and stronger hydrogen bonds between ADN and water molecules could possibly be the main reason of the severe hygroscopicity of ADN.

A general approach has been developed to synthesize high-quality Cu−In−S based multicomponent solid-solution nanocrystals (NCs) of Zn2x(CuIn)1−xS2, (CuIn)1−xCd2xS2, and (ZnS)x(CuInS2)y(CdS)z at relatively low temperature. This was achieved in a noncoordinating solvent system (toluene) by a simple solvothermal process using metal diethyldithiocarbamate complexes as the precursors. The composition, crystalline structure, size, and bang gap of the NCs could be readily tuned by the precursors used and synthesis conditions. This work provides useful understanding for the synthesis of solid-solution NCs that are of interest for photocatalyst, solar cell, and other applications.

A selective oxidation of alcohols to corresponding carbonyl compounds in room temperature ionic liquid (IL) [bmim]BF4 was achieved by using novel amino acid Schiff base copper ligand. The catalytic system can be recycled and reused for five runs without any significant loss of catalytic activity.