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1.
Jun Jiang Yuanyuan Jing Yaofa Zhang Na Zhang Jiemin Jiao Weimin Zhu Huazhen Xue Yongli Zong Guanyu Yang 《Catalysis Letters》2011,141(4):544-548
Abstract
Benzoic acid could be efficiently prepared from aerobic oxidation of toluene using manganese dioxide (MnO2) and N-hydroxyphthalimide (NHPI) as catalysts. The conditions of oxidation, including temperature, amount of catalyst, dioxygen pressure and reaction time, were studied in details. Thus 94.4% conversion of toluene and 98.4% selectivity of benzoic acid could be obtained at 110 °C under 0.3 MPa for 3 h in the presence of 10 mol% NHPI and 4 mol% MnO2. 相似文献2.
Shanhui Zhu Yulei Zhu Shunli Hao Lungang Chen Bin Zhang Yongwang Li 《Catalysis Letters》2012,142(2):267-274
Abstract
Hydrogenolysis of glycerol to 1,3-propanediol in aqueous-phase was investigated over Pt-H4SiW12O40/SiO2 bi-functional catalysts with different H4SiW12O40 (HSiW) loading. Among them, Pt-15HSiW/SiO2 showed superior performance due to the good dispersion of Pt and appropriate acidity. It is found that Br?nsted acid sites facilitate to produce 1,3-PDO selectively confirmed by Py-IR. The effects of weight hourly space velocity, reaction temperature and hydrogen pressure were also examined. The optimized Pt-HSiW/SiO2 catalyst showed a 31.4% yield of 1,3-propanediol with glycerol conversion of 81.2% at 200 °C and 6 MPa. 相似文献3.
Ferula orientalis L. stalks were liquefied in an autoclave in supercritical organic solvents (methanol, ethanol, 2-propanol, acetone and 2-butanol) with (NaOH, Na2CO3, ZnCl2) and without catalyst at five different temperatures ranging from 240 °C to 320 °C. The amounts of solid (unconverted raw material), liquid (bio-oil) and gas produced, as well as the composition of the resulting liquid phase, were determined. The effects of various parameters such as temperature, solvent, catalyst and ratio of catalyst on product yields were investigated. The results showed that conversion highly depends on the temperature and catalyst. The highest bio-oil yield (53.97%) was obtained using acetone with 10% zinc chloride at 300 °C. The liquid products were extracted with benzene and diethyl ether. Some of selected liquid products (bio-oils) were analyzed by elemental, FT-IR and GC–MS. 126 different compounds were identified by GC–MS in the liquid products obtained in ethanol at 300 °C. 相似文献
4.
The selective oxidation of glycerol and 5-hydroxymethylfurfural (HMF) to diacids over supported gold catalysts (Au/C and Au/TiO2) in liquid water at mild temperatures was a strong function of the added base such as NaOH. Use of hydrotalcite as a solid base in place of NaOH in the HMF reaction medium facilitated the production of diacid over Au/TiO2, but extensive leaching of magnesium suggested that hydrotalcite was consumed stoichiometrically in the reaction. Production of diacids from glycerol oxidation over supported Au catalysts was promoted by operating in a continuous flow reactor and by increasing the catalyst loading in a semi-batch reactor. Trace inhibitors formed by conversion of the product monoacid are proposed to account for the generally low selectivity to diacids over gold catalysts. 相似文献
5.
Endalkachew Sahle-Demessie Venu Gopal Devulapelli 《Applied catalysis. B, Environmental》2008,84(3-4):408-419
The removal of volatile and odorous emissions from pulp and paper industrial processes usually generates secondary pollution which is treated further by scrubbing, adsorption, and catalytic incineration. Studies using a flow reactor packed with 10% vanadia/titania (V2O5/TiO2) catalyst showed complete conversion of dimethyl sulfide (DMS) in the presence of ozone. The molar yields of partial oxidation products were only 10–20%. Small amounts of partial oxidation products, such as and dimethyl sulfone (DMSO2), dimethyl disulfide (DMDS), and dimethyl sulfoxide (DMSO), were also formed. The results of the oxidation of DMS using ozone only, ozone plus catalyst, and oxygen plus catalyst suggest that the combined use of O3 with catalyst is essential for the complete destruction of DMS to CO2 and SO2. A Box-Behnken design was used to determine the factors that have a significant effect on the conversion and selectivity of the products. It was concluded that product selectivity is strongly influenced by temperature, gas hourly space velocity (GHSV), and ozone concentration. The catalysts were characterized using XRD, surface area measurements, and SEM techniques. Time-on-stream studies carried out in a 500 ppmv gas stream held at 150 °C for 6 h, using 2 g of the catalyst, an ozone-to-DMS molar ratio of 0.9, and a GHSV of 37,000 h−1, yielded 99.9% conversion of DMS. A plausible reaction mechanism has been proposed for the oxidation of DMS based on reaction product distribution and possible intermediates formed. 相似文献
6.
Abstract
In this work, we prepared a new magnetically recoverable CoO catalyst through the deposition of the catalytic active metal nanoparticles of 2–3 nm on silica-coated magnetite nanoparticles to facilitate the solid separation from liquid media. The catalyst was fully characterized and presented interesting properties in the oxidation of cyclohexene, as for example, selectivity to the allylic oxidation product. It was also observed that CoO is the most active species when compared to Co2+, Co3O4 and Fe3O4 in the catalytic conditions studied. 相似文献7.
《Applied catalysis. B, Environmental》2009,85(3-4):408-419
The removal of volatile and odorous emissions from pulp and paper industrial processes usually generates secondary pollution which is treated further by scrubbing, adsorption, and catalytic incineration. Studies using a flow reactor packed with 10% vanadia/titania (V2O5/TiO2) catalyst showed complete conversion of dimethyl sulfide (DMS) in the presence of ozone. The molar yields of partial oxidation products were only 10–20%. Small amounts of partial oxidation products, such as and dimethyl sulfone (DMSO2), dimethyl disulfide (DMDS), and dimethyl sulfoxide (DMSO), were also formed. The results of the oxidation of DMS using ozone only, ozone plus catalyst, and oxygen plus catalyst suggest that the combined use of O3 with catalyst is essential for the complete destruction of DMS to CO2 and SO2. A Box-Behnken design was used to determine the factors that have a significant effect on the conversion and selectivity of the products. It was concluded that product selectivity is strongly influenced by temperature, gas hourly space velocity (GHSV), and ozone concentration. The catalysts were characterized using XRD, surface area measurements, and SEM techniques. Time-on-stream studies carried out in a 500 ppmv gas stream held at 150 °C for 6 h, using 2 g of the catalyst, an ozone-to-DMS molar ratio of 0.9, and a GHSV of 37,000 h−1, yielded 99.9% conversion of DMS. A plausible reaction mechanism has been proposed for the oxidation of DMS based on reaction product distribution and possible intermediates formed. 相似文献
8.
Sara E. Davis Levi R. Houk Erin C. Tamargo Abhaya K. Datye Robert J. Davis 《Catalysis Today》2011,160(1):111
Supported Pt, Pd, and Au catalysts were evaluated in the aqueous-phase oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) at 295 K and high pH in a semibatch reactor. The intermediate reaction product 5-hydroxymethyl-2-furancarboxylic acid (HFCA) was formed in high yield over Au/C and Au/TiO2 at 690 kPa O2, 0.15 M HMF and 0.3 M NaOH, but did not continue to react substantially to FDCA at the specified O2 pressure and base concentration. In contrast, the final reaction product FDCA was formed over Pt/C and Pd/C under identical conditions. The initial turnover frequency of HMF conversion was an order of magnitude greater on Au catalysts compared to either Pt or Pd. Increasing the O2 pressure and NaOH concentration facilitated the conversion of HFCA to FDCA over the supported Au. The significant influence of base concentration on the product distribution indicates an important role of OH− in the activation, oxidation and degradation of HMF. 相似文献
9.
Churchil A. Antonyraj Jaewon Jeong Bora Kim Seunghan Shin Sangyong Kim Kwan-Young Lee Jin Ku Cho 《Journal of Industrial and Engineering Chemistry》2013,19(3):1056-1059
Selective oxidation of 5-hydroxymethyl-2-furfural (HMF) to 2,5-diformylfuran (DFF) toward industrial production was studied over Ru supported γ-alumina catalyst using molecular oxygen as an oxidant. From the solvents screening, considering recyclability after reaction, toluene was found to be the best solvent and gave maximum conversion of 99% with 97% DFF selectivity at 130 °C and 40 psi O2 pressure. Catalyst was washed with NaOH solution of pH = 12 to remove the adsorbed polymer impurities and then reused up to 5 cycles. The product could be purified by simple evaporation of the solvent, which could add advantage for industrial process. 相似文献
10.
An integrated catalytic approach for the production of hydrogen by glycerol reforming coupled with water-gas shift 总被引:1,自引:0,他引:1
Edward L. Kunkes Ricardo R. Soares Dante A. Simonetti James A. Dumesic 《Applied catalysis. B, Environmental》2009,90(3-4):693-698
Reaction kinetics measurements of glycerol conversion on carbon-supported Pt-based bimetallic catalysts at temperatures from 548 to 623 K show that the addition of Ru, Re and Os to platinum significantly increases the catalyst activity for the production of synthesis gas (H2/CO mixtures) at low temperatures (548–573 K). Based on this finding, we demonstrate a gas phase catalytic process for glycerol reforming, based on the use of two catalyst beds that can be tuned to yield hydrogen (and CO2) or synthesis gas at 573 K and a pressure of 1 atm. The first bed consists of a carbon-supported bimetallic platinum-based catalyst to achieve conversion of glycerol to a H2/CO gas mixture, followed by a second bed comprised of a catalyst that is effective for water-gas shift, such as 1.0% Pt/CeO2/ZrO2. This integrated catalytic system displayed 100% carbon conversion of concentrated glycerol solutions (30–80 wt.%) into CO2 and CO, with a hydrogen yield equal to 80% of the amount that would ideally be obtained from the stoichiometric conversion of glycerol to H2 and CO followed by equilibrated water-gas shift with the water present in the feed. 相似文献
11.
Abstract
An effective heterogeneous catalyst, CaxMg2−xO2, was prepared and tested for soybean oil transesterification with methanol. The catalysts were characterized by using X-ray diffraction , Fourier transform infrared spectra, thermo gravimetric and differential thermal analysis , and Hammett indicator method. The catalyst with Ca/Mg ratio of 1.0 and calcined at 800 °C exhibited high catalytic activities. Under the suitable transesterification conditions (methanol/oil ratio 12:1, catalyst loading 6 wt%, reaction time 5 h, at reflux of methanol), the oil conversion of 91.3% could be achieved. The catalyst can be easily recovered and reused without significant deactivation. 相似文献12.
Susumu Kitamura Takuya Su-enaga Na-oki Ikenaga Takanori Miyake Toshimitsu Suzuki 《Catalysis Letters》2011,141(6):895-905
Abstract
Steam reforming of glycerin on Ni-loaded catalyst was performed using a ZrO2-based support material. The addition of CaO to ZrO2 improved the catalyst performance, and NiO/CaO–ZrO2 afforded glycerin conversion of 88.9% with an H2 yield of 75.3% at 600 °C. Carbon formation decreased from 4.2 to 2.0% with CaO-added catalyst. Solid solution was formed with the addition of CaO to ZrO2, and it exhibited basic characteristics. Further reduction of carbon formation during the reforming reaction was achieved by using a quaternary complex oxide catalyst NiO–CeO2/CaO–ZrO2, where glycerin conversion of 96.1% and a H2 yield of 83.7% were achieved with carbon formation of 0.7% at 600 °C. 相似文献13.
Abstract
The performance of pellets of unsupported and silica-supported Co3O4 in the ammonia oxidation was investigated as a function of the particle size to investigate the utilization of the catalytically active phase in these materials. The obtained activity in terms of ammonia conversion over the silica-supported Co3O4 is higher compared to the conversion over the unsupported Co3O4, despite a lower cobalt oxide loading and more severe diffusional limitations. The effectiveness factor for the silica-supported catalyst is slightly lower than the effectiveness factor for the unsupported catalyst in the form of pellets of similar size. However, the effective utilization of cobalt within the catalyst is higher for the silica-supported catalyst, mainly due to the higher dispersion of the catalytically active phase. 相似文献14.
Tsutomu Chida Kousuke Hiromori Naomi Shibasaki-Kitakawa Naoki Mimura Aritomo Yamaguchi Atsushi Takahashi 《Journal of the American Oil Chemists' Society》2020,97(12):1365-1370
Glycerol can be effectively converted to glyceric acid, a high value-added pharmaceutical raw material, through its partial oxidation over an Au/Al2O3 catalyst under strongly basic conditions. The factors important for the highly selective production of glyceric acid were investigated experimentally. It was clarified that NaOH was involved in the glycerol activation step to a glycerol alkoxide intermediate (2, 3-dihydroxypropoxide) in the liquid phase, then glyceric acid was formed by OOH species derived from O2 on an Au catalyst in the partial oxidation step. We have newly discovered the concerted effect of NaOH and O2 in different reaction steps. 相似文献
15.
Jong Wook Bae Seon-Ju Park Yun-Jo Lee Hae-Gu Park Young-Bo Kim Dong Hyun Lee Byung-Woo Kim Myung-June Park 《Catalysis Letters》2011,141(6):799-807
Abstract
The effects of reduction temperature and reaction temperature, pressure and space velocity on iron-based K/FeCuAlO x Fischer–Tropsch catalysts prepared by co-precipitation were investigated. The catalyst reduced at 150 °C deactivated quickly due to an abundance of unreduced iron species. With increasing reduction temperature, the iron oxide’s phase transformed from hematite (α-Fe2O3) to magnetite (Fe3O4) and finally to metallic iron (α-Fe). The induction period to reach steady-state catalytic activity was reduced at increased reduction temperatures due to in situ reduction by syngas during reaction. CO conversion increased with increasing reaction temperature, and selectivity to C5+ decreased with increasing reaction pressure and space velocity. At reaction temperatures up to of 300 °C, CO2 formation by the water–gas shift reaction was linearly correlated with the extent of CO conversion, and CO2 formation was slightly suppressed at ≥350 °C by a reverse water–gas shift reaction. 相似文献16.
Yuanqing Liu Nagaraju Pasupulety Kamalakar Gunda Garry L. Rempel Flora T. T. Ng 《Topics in Catalysis》2014,57(17-20):1454-1462
The effect of preparation methods on the Cu/ZnO/Al2O3 catalyst structure and catalytic activity on liquid glycerol hydrogenolysis to 1,2-propanediol has been investigated. The physicochemical properties of the catalysts were characterized by BET, XRD, TG/DTA, NH3-TPD and TPR. The experimental results showed that the catalyst prepared by an oxalate gel–coprecipitation had the highest activity. At 200 °C and 400 psi hydrogen pressure, the glycerol conversion and 1,2-propanediol selectivity catalyzed by the Cu/ZnO/Al2O3 catalyst prepared via oxalate gel–coprecipitation were 92.3 and 94.5 % respectively. It was found that the 1,2-propanediol selectivity was dependent on hydrogen pressure and the un-desired by-products were mainly due to the side reactions caused by the presence of the intermediate acetol. 相似文献
17.
Abstract
Co catalysts, obtained from a layered double Co–Zn–Al hydroxide, are highly active and stable towards the hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO) in aqueous media. The Co-673 catalyst, containing a CoO species, provided a glycerol conversion of 67.7% and a 1,2-PDO selectivity of 50.5%. The Co-873 catalyst comprising 16 nm Co nanoparticles gave a glycerol conversion of 70.6% and a 1,2-PDO selectivity of 57.8%. It was revealed that the CoO species in the Co-673 catalyst was readily converted to 50 nm Co particles under the glycerol hydrogenolysis conditions. The Co catalysts maintained a stable size and phase in recycling tests. 相似文献18.
A Ni-Cu-SiO2 nanocomposite was studied as a catalyst for vapor-phase glycerol hydrogenation to produce 1,2-propanediol (1,2-PDO). Substitution of a small amount (3 wt%) of Ni for Cu is beneficial for decreasing the Cu particle size, which would be advantageous for attaining higher 1,2-PDO selectivity and higher glycerol conversion. 92% 1,2-PDO selectivity and 100% glycerol conversion were obtained at 220 °C, 30 bar, and a weight hourly space velocity of 0.5 h− 1 over Ni(3)-Cu(77)-SiO2, which were nearly identical to those obtained with the conventional copper chromite (CuO-Cr2O3) catalyst. Therefore, the present Ni(3)-Cu(77)-SiO2 nanocomposite is regarded as a green and efficient catalyst for glycerol conversion into more valuable 1,2-PDO. 相似文献
19.
《Catalysis communications》2004,5(6):321-326
The catalytic liquid phase benzylation of benzene to diphenylmethane (DPM) with benzyl chloride (BC) is investigated over a number of zeolite catalysts at 358 K and under atmospheric pressure. Conventional homogeneous Lewis acid catalyst, AlCl3, is also included for comparison. Zeolite H-β is found to be more selective but less active compared to HY and H-ZSM-5 zeolites in the benzylation of benzene. The conversion of BC, rate of BC conversion and selectivity to DPM over H-β after 6 h of reaction time are 33.3 wt%, 4.7 × 10−3 mmol g−1 h−1 and 89.1 wt%, respectively. For comparison, the conversion of BC, rate of BC conversion and selectivity to DPM over AlCl3, under identical reaction condition, are found to be 100 wt%, 170 × 10−3 mmol g−1 h−1 and 58 wt%, respectively. Higher amounts of consecutive products are obtained over AlCl3 due to its non shape selectivity. The acidity of the zeolite catalysts is measured by temperature programmed desorption method. The effect of the duration of the run, SiO2/Al2O3 ratio of H-β, catalyst concentration, reaction temperature and benzene to BC molar ratio on the catalyst performance is also investigated in order to optimize the conversion of BC and selectivity for DPM. The conversion of BC using H-β is increased with the increase in the reaction time, catalyst concentration, reaction temperature and molar ratios whereas it decreases with the increase in SiO2/Al2O3 molar ratio of H-β. H-β is recycled two times and a slight decrease in BC conversion is observed after each cycle, which is related to the minor dealumination of the zeolite catalyst by HCl, which is produced during the reaction as by product. The formation of DPM is explained by an electrophilic attack of the benzyl cation (C6H5CH2+) on the benzene ring, which is produced by the polarization of BC over acidic sites of the zeolite catalysts. 相似文献
20.
J. Requies M. B. Güemez A. Iriondo V. L. Barrio J. F. Cambra P. L. Arias 《Catalysis Letters》2012,142(4):417-426