Co-reporter:Zi-qing Wang;Yuan-sheng Bai;Wei Jiang
Chinese Journal of Polymer Science 2017 Volume 35( Issue 1) pp:130-140
Publication Date(Web):2017 January
DOI:10.1007/s10118-017-1887-8
Mg-Al mixed oxides with different Mg/Al molar ratio were prepared by thermal decomposition of hydrotalcitelike precursors at 500 °C for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate with 1,4-butanediol to synthesize high-molecular-weight poly(butylene carbonate) (PBC). The structure-activity correlations of these catalysts in this transesterification process were discussed by means of various characterization techniques. It was found that the chain growth for the formation of PBC can only be obtained through connecting ―OH and ―OC(C)OC6H5 end-group upon removing the generated phenol, and the sample with Mg/Al molar ratio of 4.0 exhibited the best catalytic performance, giving PBC with Mw of 1.64 × 105 g/mol at 210 °C for 3.0 h. This excellent activity depended mainly on the specific surface area and basicity rather than pore structure or crystallite size of MgO.
Co-reporter:Dongxia Yan, Jiayu Xin, Chunyan Shi, Xingmei Lu, Lingli Ni, Gongying Wang, Suojiang Zhang
Chemical Engineering Journal 2017 Volume 323(Volume 323) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.cej.2017.04.021
•A green process using ILs as solvents and co-catalysts for HMF oxidation was developed.•A novel non-noble metal catalyst was used for HMF oxidation without additional base.•The catalyst was stable and its catalytic activity was remained during the reaction process.Base-free conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) was carried out by a simple and green process based on a novel ionic liquid (IL)-promoted non-noble metal catalytic reaction system. Among various of ILs, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was found to be the best IL without addition of base as it has stronger hydrogen bonds formation ability and good thermal stability, as well as free to form definite aggregates. In addition, a series of non-noble metal catalysts containing Ce, Fe, Zr were synthesized and the Ce0.5Fe0.15Zr0.35O2 catalyst was found to have excellent activity due to the existence of active iron and zirconium species and the formation of CeO2-based solid solution, which could create more oxygen vacancies and improve the redox properties of catalyst. Under the optimal reaction condition, almost complete HMF conversion and 44.2% FDCA yield were obtained after 24 h at 160 °C over Ce0.5Fe0.15Zr0.35O2 in [Bmim]Cl. More importantly, the catalyst could be reused without significant decrease of its catalytic activity. This research not only develops a more environmentally friendly catalytic system that promotes the base-free oxidation of HMF into FDCA, but also provides an economic route to produce FDCA.
Co-reporter:Xia Yin, Yi Zeng, Jie Yao, Hua Zhang, Zhiyong Deng, and Gongying Wang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 49) pp:19087-19093
Publication Date(Web):November 19, 2014
DOI:10.1021/ie502989y
The kinetic behavior of preparing diphenyl carbonate by the transesterification of dimethyl carbonate with phenol in a reactive distillation reactor has been explored experimentally and theoretically. The transesterification reaction was described to conform a pseudo-second-order kinetics, and a semi-empirical kinetic model has been derived to explain the kinetic behavior. The model parameters were fitted to experimental data by an improved genetic algorithm. The proposed model was determined to be useful in simulating the rate constant and the mole fraction of components, which agreed well with the experimental data for different operating temperatures and catalyst concentrations.
Co-reporter:Lilei Zhang;Shaoying Liu
Reaction Kinetics, Mechanisms and Catalysis 2014 Volume 112( Issue 1) pp:249-265
Publication Date(Web):2014/06/01
DOI:10.1007/s11144-014-0691-5
The catalytic combustion of dichloromethane (DCM) was examined over NaFAU and HFAU zeolites by experimental and theoretical studies. The reactions yielded carbon monoxide, hydrogen chloride, water, and methyl chloride as major products. The order of reaction was one with respect to DCM concentration, and the activation energy and pre-exponential factors were determined. Insight into the mechanism of catalytic combustion of DCM was gained by the B3LYP/6-31G(d, p) method using the 15T (T = Si or Al tetrahedral) cluster model of FAU zeolite. The results revealed that the combustion of DCM was catalyzed by FAU zeolite via the stepwise mechanism involving adsorption, dechlorination, hydrolysis, and oxidation steps in humid air. NaFAU was found to be more active than HFAU because it facilitated the adsorption and dechlorination steps, which was in agreement with the experimental result. The transformation between NaFAU and HFAU requires low activation energy (∆E = 19.2 kJ mol−1). The calculated activation barriers for the dechlorination and hydrolysis steps over NaFAU and HFAU were 82.1 and 124.2 kJ mol−1, respectively. Dechlorination of DCM was predicted to be the rate-determining step. The calculated apparent activation barrier for the combustion of DCM over NaFAU was 86.0 kJ mol−1, which was consistent with the experimental value of 84.8 kJ mol−1.
Co-reporter:Xi Zhou, Hong Ping Zhang, Gong Ying Wang, Zhi Gang Yao, Ying Ran Tang, Shan Shan Zheng
Journal of Molecular Catalysis A: Chemical 2013 Volume 366() pp:43-47
Publication Date(Web):January 2013
DOI:10.1016/j.molcata.2012.09.006
A zeolitic imidazolate framework (ZIF-8) was developed as a novel efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate from dimethyl carbonate and diethyl carbonate. ZIF-8 was characterized by element analysis, X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), temperature programmed desorption (TPD), N2 adsorption–desorption and thermogravimetric analysis. The effects of catalyst amount, temperature and reaction time on the yield of ethyl methyl carbonate were also tested. The results showed that ZIF-8 performed excellent activity, selectivity and reusability under mild reaction conditions.Graphical abstractThe zeolitic imidazolate framework (ZIF-8) was developed as a novel efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate from dimethyl carbonate and diethyl carbonate. Under optimal reaction conditions, the yield of EMC reached at 50.7%. After simple separation, ZIF-8 can be reused at least 3 times without viewable loss of activity, and the framework of ZIF-8 was well retained.Highlights► ZIF-8 was developed as a novel efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate. ► ZIF-8 performed excellent activity, selectivity and reusability. ► The framework of ZIF-8 contains acid and basic bi-active centers. ► The framework of ZIF-8 is well retained in the title reaction system.
Co-reporter:Xi Zhou, Yi Zhang, Xiangui Yang, Liangzhong Zhao, Gongying Wang
Journal of Molecular Catalysis A: Chemical 2012 Volumes 361–362() pp:12-16
Publication Date(Web):September 2012
DOI:10.1016/j.molcata.2012.04.008
Functionalized isoreticular metal–organic framework-3 (IRMOF-3) was developed as a novel heterogeneous catalyst for the solventless synthesis of cyclic carbonates without any co-catalyst. The results showed that functionalized IRMOF-3 performed excellent activity, selectivity and reusability. The effects of reaction temperature, pressure, and time on the yield of propylene carbonate were tested. And the reaction mechanism was also discussed.Graphical abstractFunctionalized IRMOF-3 was developed as a novel heterogeneous catalyst for the solventless synthesis of cyclic carbonates without any co-catalyst. It performs excellent catalytic activity and selectivity. After simple separation, it can be reused without viewable loss of activity. And the framework can be retained after the coupling reaction.Highlights► Functionalized IRMOF-3 was developed as a novel heterogeneous catalyst for the synthesis of cyclic carbonates. ► F-IRMOF-3 performed excellent activity and reusability without any co-catalyst. ► The framework of functionalized IRMOF-3 contains acid (Zn2+) and basic (I−) bi-active centers. ► There are synergetic catalytic effect between acid and basic centers.
Co-reporter:Bin Xiao, Li Ping Wang, Ren Hao Mei, Gong Ying Wang
Chinese Chemical Letters 2011 Volume 22(Issue 6) pp:741-744
Publication Date(Web):June 2011
DOI:10.1016/j.cclet.2010.12.036
Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR. It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthesis of poly(ethylene terephthalate) (PET). It was only used as polycondensation catalyst because it was sensitive to water. For this catalyst, the degree of esterification of the theoretical amount of water was produced up to 95% at 260 °C, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PET polyester, polymerized at 280 °C, 70 Pa for 39 min, was 0.87 dL/g and 23.0 μmol/g, respectively. Ethylene glycol aluminum was a promising catalyst for the synthesis of PET polyester.
Co-reporter:LiPing Wang;Bin Xiao;JiQian Wu
Science China Chemistry 2011 Volume 54( Issue 9) pp:1468-1473
Publication Date(Web):2011/09/01
DOI:10.1007/s11426-011-4284-0
The metal-organic framework Zn4O[1,4-benzenedicarboxylate]3 (Zn4O[CO2-C6H4-CO2]3, commonly known as MOF-5, was prepared by the ultrasonic irradiation method. The catalyst was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was then used as the catalyst for the preparation of polycarbonate diol (PCDL) via the transesterification between diphenyl carbonate (DPC) and 1, 6-hexandiol (1, 6-HD). Its catalytic activity in the transesterification process is evaluated by the yield of phenol, and its catalytic activity in the polycondensation process is determined by the number-average molecular weight (Mn) and the hydroxyl value. Compared to the triethylenediamine (C6H12N2), Mg-Al layered double hydroxide (Mg-Al LDH), sodium ethoxide (C2H5ONa) and sodium methoxide (CH3ONa), MOF-5 exhibits highest catalytic activity for the preparation of PCDL. Under reaction conditions (n (1,6-HD)/n(DPC) = 1.2, w(catalyst) = 0.03%, 198 °C), the yield of phenol is up to 90.1% and the PCDL shows highest Mn and lowest hydroxyl value.
Co-reporter:Shu Yong Jia, Yu Rong Ren, Gong Ying Wang
Chinese Chemical Letters 2010 Volume 21(Issue 3) pp:357-360
Publication Date(Web):March 2010
DOI:10.1016/j.cclet.2009.10.015
Chelate tetra(acetylacetonato) tin (IV) was prepared and used as catalyst for polytrimethylene terephthalate synthesis. It exhibited higher catalytic activity than tetrabutyl titanate, butyltinhydroxide oxide and dibutyltin oxide. Decrease in reaction time, content of terminal carboxyl group, color intensity and increase in intrinsic viscosity were observed. The unique molecular structure can be considered as factor remarkably improving the catalytic activity of tetra(acetylacetonato) tin (IV).
Co-reporter:Cong-Ming Tang, Yi Zeng, Xian-Gui Yang, Yong-Cheng Lei, Gong-Ying Wang
Journal of Molecular Catalysis A: Chemical 2009 314(1–2) pp: 15-20
Publication Date(Web):
DOI:10.1016/j.molcata.2009.08.008
Co-reporter:Dongshen Tong;Tong Chen;Fei Ma;Tao Kang
Reaction Kinetics, Mechanisms and Catalysis 2008 Volume 94( Issue 1) pp:121-129
Publication Date(Web):2008 June
DOI:10.1007/s11144-008-5272-z
Mo-Cu bimetallic oxides were found to be efficient heterogeneous catalysts for the transesterification of dimethyl carbonate (DMC) with phenol. When the reaction was carried out between 150 and 180°C, with a molar of Mo/Cu of 1:1, molar ratio of phenol/DMC of 1:1, 4.8 wt.% of the catalyst, 9 h, the conversion of phenol was 49.9%, and the total yield of MPC and DPC was 45.4%. Catalyst reuse showed a gradual decline in the catalytic activity. The decrease in catalytic activity might be due to leaching out of Mo and Cu, and/or carbon deposition.
Co-reporter:ShuYong Jia;YuRong Ren;Dan Zhang;Jing Hu
Science China Chemistry 2008 Volume 51( Issue 3) pp:257-262
Publication Date(Web):2008 March
DOI:10.1007/s11426-007-0124-7
A complete study on the catalytic activity of stannous oxalate for poly(trimethylene terephthalate) (PTT) synthesis via esterification method is carried out by comparison to the well known catalysts (tetrabutyl titanate (TBT), dibutyltin oxide (Bu2SnO), and stannous octoate (SOC)). Their catalytic activity in the esterification process is monitored by measuring the amount of water generated, while intrinsic viscosity (IV) and content of terminal carboxyl groups (CTCG) are used as the index in the polycondensation process. Stannous oxalate shows higher activity than the other catalysts. Decrease in reaction time and improvements in PTT property are observed. The higher catalytic activity of stannous oxalate is attributed to its chelate molecular structure.
Co-reporter:Shaoying Liu;Yanxiao Chen
Journal of Applied Polymer Science 2007 Volume 105(Issue 5) pp:2841-2849
Publication Date(Web):16 MAY 2007
DOI:10.1002/app.26025
The flocculation characteristics of cationic starches with degree of substitution (DS 0.32–0.63) have been evaluated in 1.0 wt % kaolin suspension by spectrophotometry and colloid titration. Cationic starch is found to be an effective flocculant for removal of anionic suspension particles. Changes in the electrokinetics of kaolin as a function of pH were investigated in the absence of flocculant. The results show that kaolin in water exhibits a negative surface charge at pH > 2.5. The negative hydrophilic surface sites of kaolin are responsible for the adsorption of cationic starch molecules. The experimental data of the adsorption of cationic starch (DS 0.51) follow a Langmuir isotherm with maximum adsorption capacities of 16.89 mg/g. For the adsorption of cationic starch, chemical reaction seems significant in the rate-controlling step and the pseudosecond-order chemical reaction kinetics provides the best correlation for the experimental data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Ke Bing Wang, Gong Ying Wang
Chinese Chemical Letters 2007 Volume 18(Issue 7) pp:811-813
Publication Date(Web):July 2007
DOI:10.1016/j.cclet.2007.05.004
The condensation reaction of formaldehyde and methyl formate to form methyl glycolate and methyl methoxy acetate catalyzed by p-toluenesulfonic acid and different Lewis acid compounds has been investigated. The composite catalytic system consisting of p-toluenesulfonic acid and NiX2 (X = Cl, Br, I), especially NiI2, exhibited a high catalytic performance for the condensation reaction, the total yield of MG and MMAc was up to 72.37%.
Co-reporter:Shu Yong Jia, Yu Rong Ren, Liang Ming Liu, Dan Zhang, Yi Zeng, Gong Ying Wang
Chinese Chemical Letters 2007 Volume 18(Issue 7) pp:827-830
Publication Date(Web):July 2007
DOI:10.1016/j.cclet.2007.05.019
Stannous-acetylacetonate was prepared efficiently and characterized by 1H NMR and FT-IR. Its catalytic activity for poly(trimethylene terephthalate) (PTT) synthesis was investigated. By this catalyst, the degree of esterification of pure terephthalic acid was up to 91.7% after reaction at 260 °C for 2 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polymerized at 260 °C, 60 Pa for 2 h was 0.8816 dL/g and 17 mol/t, respectively. Stannous-acetylacetonate was more active and promising than tetrabutyl titanate and stannous octoate for PTT synthesis.
Co-reporter:Yanxiao Chen, Shaoying Liu, Gongying Wang
Journal of Colloid and Interface Science 2006 Volume 303(Issue 2) pp:380-387
Publication Date(Web):15 November 2006
DOI:10.1016/j.jcis.2006.08.011
The adsorption of carboxymethyl starch (CMS) at the α-alumina/aqueous solution interface has been investigated through adsorption studies, electrokinetics mobility measurements, and FTIR spectroscopy. Zeta potential measurements show that the addition of CMS results in a more dramatic increase in the absolute zeta potential in the alkaline region, as well as a shift of the isoelectric point to lower values, indicating the adsorption of CMS from the aqueous solution onto the alumina surface. The positive hydrophilic surface sites of alumina are responsible for the adsorption of CMS molecules. The adsorption of CMS is possible after charge reversal by the addition of excess CMS. Nearly 30 min of contact time are found to be sufficient for the adsorption of CMS to reach equilibrium. CMS adsorption follows a Langmuir isotherm with adsorption capacities of 91.74 mg CMS per gram of α-alumina. For the adsorption of CMS, pseudo-second-order chemical reaction kinetics provides the best correlation with the experimental data. FTIR analysis indicated that CMS forms outer complexes with alumina surfaces depending on the shifting of the asymmetric and symmetric bands.The adsorption mechanism of carboxymethyl starch at acidic pH values was investigated on α -alumina through electrokinetic and the Fourier transform infrared (FTIR) spectroscopy. The experimental results of the specific energy of interaction (ΔG0ΔG0), the pseudo-second-order model, and FTIR studies indicated that CMS is chemisorbed onto the alumina surfaces by forming a chelate complex.
Co-reporter:Gongying Wang;Yanxiao Chen
Journal of Applied Polymer Science 2006 Volume 102(Issue 2) pp:1539-1546
Publication Date(Web):28 JUL 2006
DOI:10.1002/app.23323
Cornstarch, after crosslinking with epichlorohydrin (4%, v/w, dry basis of the starch), was oxidized with hydrogen peroxide over the catalyst Cu(II). The newly synthesized products were applied to examine the calcium ion removal activity from water, under various conditions. Removal efficiency of calcium ion from aqueous solution increased proportionally with carboxyl content and the dose of crosslinked oxidized starch in the solution. Ionization of carboxyl groups in starch was necessary for the effective calcium removal. When the pH of the solution was adjusted below 4.0, the starch was no longer an effective calcium-sequestering agent. Adsorption isotherm models were developed, wherein the best fit was obtained in the Langmuir model. Thermodynamic study indicated that the adsorption process was exothermic, and the enthalpy change (ΔHθ), the entropy change (ΔSθ), and free energy change (ΔGθ) of the adsorption process were calculated with adsorption isotherm data and basic thermodynamic relations. It was assessed that adsorption occurred by strong electrostatic interactions with the negative adsorption enthalpy (ΔHθ). The regeneration and reusability of oxidized starch were also assessed and were found to retain the adsorption capacity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1539–1546, 2006
Co-reporter:Yan-Xiao Chen, Gong-Ying Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2006 Volume 289(1–3) pp:75-83
Publication Date(Web):15 October 2006
DOI:10.1016/j.colsurfa.2006.04.008
The adsorption properties of oxidized carboxymethyl starch (OCMS) and cross-linked carboxymethyl starch (CCMS) with carboxymethyl groups for calcium ion in aqueous solution were investigated. Removal efficiency of calcium ion from aqueous solution was found to be dependent on initial concentration of calcium ion, the adsorbent dose and temperature. Ionization of carboxymethyl groups in OCMS and CCMS was necessary for the effective calcium removal. When the pH of the solution was adjusted below 4.0, OCMS and CCMS were no longer an effective calcium-sequestering agent. Regardless of starch type, the adsorption capacities of two anionic starches reached a state of equilibrium within 30 min for starch dispersion in calcium salt solution. Adsorption of calcium ion followed modified Freundlich kinetics with the adsorption rate for adsorption on OCMS being higher followed by that on CCMS. The adsorption rate constant was found to decrease with the increase in the temperature. Adsorption isotherm models were developed wherein the best fit was obtained in the Langmuir model for OCMS and Freundlich isotherm for CCMS, respectively. Thermodynamic study indicated that the adsorption process of calcium ion on two anionic starches was exothermic, and the enthalpy change (ΔHθ), the entropy change (ΔSθ), and free energy change (ΔGθ) of the adsorption process were calculated with adsorption isotherm data and basic thermodynamic relations. It was assessed that adsorption occurred by strong electrostatic interactions with the negative adsorption enthalpy.
Co-reporter:Hongying Niu, Jie Yao, Yue Wang, Gongying Wang
Journal of Molecular Catalysis A: Chemical 2005 Volume 235(1–2) pp:240-243
Publication Date(Web):1 July 2005
DOI:10.1016/j.molcata.2005.03.023
Titanocene dichloride (Cp2TiCl2) was found to be a novel and efficient catalyst for the transesterification between dimethyl carbonate (DMC) and phenol to diphenyl carbonate (DPC). Compared with other titanium esters, Cp2TiCl2 is more stable in air and can reach maximum catalytic activity at low catalyst amount. When the reaction was carried out between 150 and 180 °C, with a molar ratio of phenol to DMC of 1:1, a reaction time 10 h, a catalyst amount 0.5% (molar ratio to phenol), the conversion of phenol was 46.8%, and the selectivity of DPC and MPC was 54.9 and 43.4%, respectively.Titanocene dichloride (Cp2TiCl2) was found to be a novel and efficient catalyst for this reaction. Cp2TiCl2 is more stable in air condition than other titanium esters and can enhance the conversion of phenol greatly, and it can reach its maximum catalytic activity at low catalyst amount.
Co-reporter:Kebing Wang, Jie Yao, Yue Wang, Gongying Wang
Journal of Natural Gas Chemistry (September 2007) Volume 16(Issue 3) pp:286-292
Publication Date(Web):1 September 2007
DOI:10.1016/S1003-9953(07)60061-9
The coupling reaction of formaldehyde (FA) and methyl formate (MF) to form methyl glycolate (MG) and methyl methoxy acetate (MMAc), catalyzed by p-toluenesulfonic acid (p-TsOH) as well as assisted by different kinds of solvents or Ni-containing compounds, had been investigated. The results showed that when the reaction was carried out at 140 °C, with a molar ratio of FA to MF of 0.65: 1, molar fraction of p-TsOH to total feedstock of 11.0%, and reaction time of 3 h, the yield of MG and MMAc was 31.1% and 17.1%, respectively. p-TsOH catalyzed the coupling reaction by means of the synergistic catalysis of protonic acidity and soft basicity. Adding extra solvents to the reaction system was unfavorable for the reaction. The composite catalytic system consisting of p-TsOH and NiX2 (X=Cl, Br, I) exhibited a high catalytic performance for the coupling reaction, and NiX2 acted as a promoter in the reaction, whose promotion for the catalysis increased in the following order: NiCl2
Co-reporter:Yanping FAN, Qingyin WANG, Xiangui YANG, Jie YAO, Gongying WANG
Chinese Journal of Chemical Engineering (October 2009) Volume 17(Issue 5) pp:883-886
Publication Date(Web):1 October 2009
DOI:10.1016/S1004-9541(08)60292-X
The catalytic properties of KF/MgO for the synthesis of didodecyl carbonate (DDC) by transesterification from dimethyl carbonate (DMC) and dodecanol were studied. The effects of loading amount of KF and calcining temperature were systemically investigated. The phase structure was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Interaction between KF and the carrier MgO occurred in the process of calcination, and a new phase K2MgF4 formed when calcining temperature was 673 K or above. FTIR results showed that K2CO3 was observed when catalysts calcined in air. When calcining temperature was 873 K and the loading mass amount of KF was 30%, the KF/MgO catalyst exhibited the optimal catalytic properties and the yield of DDC was maximized to 80%. The excellent catalytic properties of KF/MgO was ascribed to the formation of K2MgF4+K2CO3 during the calcination in air.
Co-reporter:Liping Wang, Bin Xiao, Gongying Wang
Journal of Natural Gas Chemistry (July 2010) Volume 19(Issue 4) pp:436-440
Publication Date(Web):1 July 2010
DOI:10.1016/S1003-9953(09)60089-X
The transesterification of diphenyl carbonate (DPC) with 1,4-butyldiol (BD) was kinetically investigated in the presence of lithium acetate catalyst at 465 K. The reaction was followed by the measurement of the quantity of phenol which was distilled from the reactor. The experiments supported the assumption that the phenyl ester groups in DPC and phenyl hdroxybutyl carbonate (PHBH) had the same reactivity, and the transesterification obeyed first-order kinetics with respect to DPC and BD, and a rate equation was derived. The reaction rate was found to be first order with respect to the catalyst concentration as well. When those data were incorporated in the rate equation, excellent agreement between calculated values and the observed ones was recognized over a wide range.
