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1.
《Journal of Energy Chemistry》2010,(6)
Combination of partial oxidation of methane (POM) with carbon dioxide reforming of methane (CRM) has been studied over Ru-based catalysts at 550℃.POM,CRM and combined reaction were performed over 8wt%Ru/γ-Al2O 3 and the results show that both POM and CRM contribute to the combined reaction,between which POM plays a more important role.Moreover,the addition of Ce to Ru-based catalyst results in an improvement in the activity and CO selectivity under the adopted reaction conditions.The Ce-doped catalyst was characterized by N2 adsorption-desorption,SEM,XRD,TPR,XPS and in situ DRIFTS.The mechanism has been studied by in situ DRIFTS together with the temperature distribution of catalyst bed.The mechanism of the combined reaction is more complicated and it is the combination of POM and CRM mechanisms in nature.The present paper provides a new catalytic system to activate CH4 and CO2 at a rather low temperature. 相似文献
2.
Low-temperature utilization of CO2 and CH4 by combining partial oxidation with reforming of methane over Ru-based catalysts
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Combination of partial oxidation of methane (POM) with carbon dioxide reforming of methane (CRM) has been studied over Ru-based catalysts at 550 ℃. POM, CRM and combined reaction were performed over 8wt%Ru/γ-Al2O3 and the results show that both POM and CRM contribute to the combined reaction, between which POM plays a more important role. Moreover, the addition of Ce to Ru-based catalyst results in an improvement in the activity and CO selectivity under the adopted reaction conditions. The Ce-doped catalyst was characterized by N2 adsorption-desorption, SEM, XRD, TPR, XPS and in situ DRIFTS. The mechanism has been studied by in situ DRIFTS together with the temperature distribution of catalyst bed. The mechanism of the combined reaction is more complicated and it is the combination of POM and CRM mechanisms in nature. The present paper provides a new catalytic system to activate CH4 and CO2 at a rather low temperature. 相似文献
3.
TEM, FTIR and XRD techniques are used to investigate the structure of HPWA-SBA-15. The results show that pores of HPWA-SBA-15 have regular two-dimensional hexagonal structure, and HPWA disperses well in the pore or pore wall of HPWA-SBA-15. NH3-TPD shows the HPWA-SBA-15 catalyst has acidic properties. ETBE is synthesized by the etherification reaction of alcohol and tert-butyl alcohol over several catalysts. Solid acid catalyst HPWA-SBA-15 is the appropriate catalyst which has the highest yield of ETBE than PW12/C and cation resin. The influences of reaction temperature, ratio of alcohol to tert-butyl alcohol are studied. At optimal operation condition, 30% HPWA on HPWA-SBA-15, reaction temperature 100℃, alcohol/tert-butyl alcohol molar ratio 2, the quality catalyst 0.9 g and raw material 10 g, the yield of ETBE is 59.55% and the selectivity is 90.2%. 相似文献
4.
WU Jin-Gang LI Shu-BenState Key Laboratory of Oxo Synthesis Selective Oxidation Lanzhou Institute of Chemical Physics Academia Sinica Lanzhou Gansu 《天然气化学杂志》1995,(3)
The oxidative coupling of methane over Mn2O3-Na2WO4/SiO2 catalyst has been investigated in the absence of dilute gas. 16.4% of C2 yield and 80.4% of the selectivity to C2 hydrocarbons were obtained at CH4/O2 = 8.5/1.5. The effect of flow rate on the selectivity to C2 hydrocarbons and CH4 conversion was different under the reaction condition of different ratio of CH4 to oxygen. The flow rate had a more remarkable effect on the selectivity at the lower ratio of methane to oxygen. The addition of steam into the reaction gas can increase C2 yield to some extent, but that of HC1 decrease the selectivity to C2 hydrocarbons. 相似文献
5.
《天然气化学杂志》1994,(2)
A comparative kinetic analysis of the title reaction over the LC andSLC catalysts is reported.It shows that there are obvious differences in the ap-parent reaction activation energies,apparent reaction orders and the pathwayfor the formation of CO_x between the LC and SLC catalysts.The apparent acti-vation energies for CH_4 conversion and C_2,CO_x production over the LC catalystare higher than those over the SLC catalyst,while preexponential factors forthe CH_4 conversion and C_2,CO_x production are in reverse order.The ratio ofk_(C_2)/k_(CH_4) over the SLC is larger than that over the LC.In contrast,the ratio ofk_(CO_x)/k_(CH_4) over the SLC is smaller than that over the LC.This suggests that therole of the SrO additive is suppression of the total oxidation of methane and re-sults in a higher C_2selectivity.The apparent orders of CH_4 and O_2are about onein CH_4 conversion over the LC catalyst while the CH_4 conversion is about secondoder reaction with respect to CH_4 adn about first order reaction with 相似文献
6.
Yejun Qiu Jixiang Chen Jiyan Zhang 《天然气化学杂志》2007,16(2):148-154
The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane (POM) to synthesis gas was investigated. It was found that the POM reaction could not be ignited over lwt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of lwt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactiorrconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species. 相似文献
7.
Weena Phongsawat Benjamas Netivorruksa Kongkiat Suriye Siraprapha Dokjampa Piyasan Praserthdam Joongjai Panpranot 《天然气化学杂志》2012,(1):83-90
An unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts has been studied as an alternative route for the production of propylene. Complete conversion of 2-pentene and propylene yield as high as 88 wt% were obtained under mild reaction conditions at 35°C and atmospheric pressure. Unlike the conventional metathesis of ethylene and 2-butenes in which isomerization is a competing side reaction, the isomerization of 1-butene product from the unconventional metathesis of ethylene and 2-pentene to 2-butenes can further react with excess ethylene in the feed, resulting in additional increase in propylene yield. The secondary metathesis reaction was found to be favored under ethylene/2-pentene (E/2P) molar ratio 3 and gas hourly space velocity (GHSV) 1000 h-1 at the reaction temperature of 35°C. No catalyst deactivation was observed during the 455 min time-on-stream under the selected reaction conditions. 相似文献
8.
The cobalt and ruthenium bimetallic complex of poly-γ-amino-propylsiloxane( abbr. as Si-CH_2-Co-Ru) was prepared, and it was found that it can catalyze the hydroformylation of cyclobexene effectively with the conversion amounting to over 90%. Cyclohexanecarboxaldehyde was first formed in the hydroformylation, and then further hydrogenated to form cylcohexanemethanol. The coversion was affected obviously by the Co/Ru ratio.When Co/Ru molar ratio was 100-150, i.e. in the very low content of noble metal Ru, the catalytic activity of Si-NH_2 -Co-Ru was also very high. The product composition was affected by CO/H_2 ratio in the reaction gas. Aldehyde can be got high selectively by controlling CO/H_2 ratio. Compared with other catalyst system, the Si-NH_2-Co-Ru catalyst has higher catalytic activity and efficiency with very low Ru/Co ratio. The total turnover number was more than 28,800 (based on the amount of ruthenium used). 相似文献
9.
Tinghua Wu Mingqiao Zhu Zhenjiang Niu Yijun Zhong Yan Guan Ya Liu Qiangu Yan Zelin Li Huilin WanZhejiang Normal University Institute of Physical Chemistry Jinhua ChinaZhejiang University Department of Chemical Engineering Hangzhou ChinaXiamen University Department of Chemistry Xiamen China 《天然气化学杂志》2002,(Z2)
The catalytic properties of several supported metal catalysts on different carriers were studied in the partial oxidation of methane (POM) to syngas. In our experiment, supported noble metal catalysts exhibited better performance than the other supported transition metal catalysts. The catalyst performances were significantly influenced by the d-electron configuration of the active metal components and the dispersion of active metal components on the support. A catalyst with a moderate number of unpaired electrons in the d-orbital of the active metal support without obvious acidity or redox activity (e.g. MgO) was suitable for POM performance. The Rh/SiO2 catalyst was the best in the POM reaction, among those investigated. Reaction conditions apparently also affected the POM performance of the catalyst. The conversion of methane and the selectivity for CO increased with the reaction temperature, and a high CH4/O2 ratio was not beneficial for POM performance. 相似文献
10.
CHEN Xu MEI Jie QIN ZhiYong SONG LingLing ZHANG XiaoBo LI XiaoYun BAO HaiFeng SHI JianJun ZHAO HuanYu 《中国科学:化学(英文版)》2013,56(4):475-480
Ball in cage structures of cobalt sulfide have been successfully prepared by a facile one-pot hydrothermal synthesis approach employing Co(NO3)2·6H2O as the cobalt source and S=C(NH2)2 as the sulfur source. The effects of the reaction parameters (volume ratio of distilled water to ethanol, reaction time and reaction temperature) on the morphology and size of the CoS structures were investigated. The synthesized product was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It has been confirmed that the volume ratio of distilled water to ethanol played a key role in the formation of the ball in cage structures, and the formation mechanism of the CoS ball in cage structures was also proposed. The electrochemical capacitance performances of the CoS products were studied, and the CoS ball in cage structures show excellent energy storage characteristics. 相似文献
11.
LI Zhong ZHANG Jun-Zhong WANG Chang-YouInstitute of Coal Chemical Engineering Taiyuan University of Technology Taiyuan Shanxi To whom correspondence should he addressed 《天然气化学杂志》1995,(3)
Hydroformylalion of 1-heptene catalyzed by homogeneous and heterogeneous Ru3(CO)12 catalyst has been investigated. Ru3(CO)12 almost has no activity when the reaction temperature is below 60℃, and nearly stable activity when over 100℃. The maximum selectivity for aldehyde is obtained at 120℃ and V/I values of aldehyde and alcohol decrease rapidly with increasing temperature. Supported Ru3(CO)12 catalysts modified with NaBH4 or KOH have higher activity and selectivity for aldehyde. Compared with supported Ru3(CO)12 catalysis, Ru3(CO)12/Co2(CO)g/γ-Al2O3 has high activity and selectivity. When PPh3 or (NKt4)Cl is added to the reaction system, the selectivity for aldehyde and the .N/I ratio increase. The FT-IR spectra of catalysts alter reaction show that Ru3(CO)12 is transformed to a hydrocarbonyl complex [HRu3(CO)11]-, and (NEt4)Cl promotes the formation of |HRu3(CO)11|- and stabilizes it. 相似文献
12.
In the partial oxidation of methane (POM) to syngas, carbon deposition on the catalyst causing catalyst deactivation or reactor plugging was reported[1~3]. Our previous work showed that methane dissociation on metallic sites to H2 and NixC is an initial step of POM over Ni/Al2O3[4]. If NixC can not be consumed immediately after its formation, it has a tendency to dissolve into the nickel crystal to form carbon whiskers. The bulk carbon and carbon whiskers are more difficult to be oxidized than NixC. Therefore, prohibiting the transformation of NixC to bulk carbon and carbon whiskers can depress the formation of carbon deposition effectively. 相似文献
13.
N. A. S. Amin Sriraj Ammasi 《天然气化学杂志》2006,15(3):191-202
A dual-bed catalytic system is proposed for the direct conversion of methane to liquid hydrocarbons. In this system, methane is converted in the first stage to oxidative coupling of methane (OCM) products by selective catalytic oxidation with oxygen over La-supported MgO catalyst. The second bed, comprising of the HZSM-5 zeolite catalyst, is used for the oligomerization of OCM light hydrocarbon products to liquid hydrocarbons. The effects of temperature (650-800℃), methane to oxygen ratio (4 10), and SiO2/Al2O3 ratio of the HZSM-5 zeolite catalyst on the process are studied. At higher reaction temperatures, there is considerable dealumination of HZSM-5, and thus its catalytic performance is reduced. The acidity of HZSM-5 in the second bed is responsible for the oligomerization reaction that leads to the formation of liquid hydrocarbons. The activities of the oligomerization sites were unequivocally affected by the SiO2/Al2O3 ratio. The relation between the acidity and the activity of HZSM-5 is studied by means of TPD-NH:j techniques. The rise in oxygen concentration is not beneficial for the C5 selectivity, where the combustion reaction of intermediate hydrocarbon products that leads to the formation of carbon oxide (CO CO2) products is more dominant than the oligomerization reaction. The dual-bed catalytie system is highly potential for directly converting methane to liquid fuels. 相似文献
14.
LIU Zhao-Tie ZHOU Jing-LaiZHANG Zhi-Xin ZHANG Bi-Jianginstitute of Cual Chemistry Academia Sinica Taiyuan Shanxi To whom correspondence should be addressed. 《天然气化学杂志》1995,(1)
The influence of reaction pressure, temperature, space velocity (GHSV), particle size of catalyst and H2/CO ratio of feed-gas on the steady-state product distribution, conversion of CO, H2 and syngas, olefin to paraffin ratio and CO2/ H2O ratio for FTS reaction were investigated using a coprecipitated copper- potassium promoted iron catalyst. The test was carried out in a fixed-bed reactor. Increasing the reaction temperature from 493. 2 to 5-13. 2 K shifted the hydrocarbon distribution toward the heavier hydrocarbons (C5-C23) and selectively increased CO conversion to CO2. The hydrocarbon distribution was found to be dependent on the H2/CO feed-gas ratio in the range from 1.23 to 2. 22. The CO2/H2O ratio in product decreased as the flow of feed-gas rate increased, which suggests that H2O is a primary product and its reaction with CO to form CO2 occurs via a secondary process. The CO conversion increased with the decrease of catalyst particle size from 10 to 60 mesh (2. 0- 0. 3 mm), while the CO convers 相似文献
15.
The mechanism for synthesis of 4,4-methylenedianiline(MDA) via condensation reaction of aniline with formaldehyde has been studied extensively in this paper.The intermediate and by-products were isolated and identified.The combination of isotope labeling and HPLC-MS characterizations disclosed that the reaction proceeded through an S_N2 reaction mechanism.Moreover,the effect of aniline/formaldehyde molar ratio on the formation of MDA was investigated.This work would be of significance to understand the reaction mechanism deeply and provide valuable information for further improving the yield of desired product. 相似文献
16.
Depolymerization of Poly(bisphenol A carbonate) in Subcritical and Supercritical Toluene 总被引:1,自引:0,他引:1
Zhi Yan PAN Zhen BAO Ying Xu CHEN 《中国化学快报》2006,17(4):545-548
The depolymerization of poly(bisphenol A carbonate)(PC) in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature (570-633 K), pressure (4.0-7.0 MPa), reaction time (5-60 min), and toluene to PC weight ratio (3.0-11.0), were investigated, and the reaction products were determined by GC, GC/MS and FT-IR spectrometer. It was found that the main product of the depolymerization reaction was bisphenol A(BPA). BPA accounted for over 55.7% of the depolymerization products at reaction temperature 613 K, pressure 5.0-6.0 MPa, reaction time 15 min and toluene/PC weight ratio of around 7.0. 相似文献
17.
The succinylation of cornstarch by slurry reaction has been studied using sodium hydroxide as catalyst.Several reaction parameters affecting the succinylation were investigated including the concentration of starch in water,the ratio of succinic anhydride to starch,the reaction time and the reaction temperature,The favorable conditions for an intermediate degree of substitution(DS) and reasonably high reaction efficiency(RE) are pH 8.5-9.0,50% starch by weight to water.succinic anhydride to starch 1/1(w/w),reaction time 4h,reaction temperature 30℃ .Under these conditions,the DS of 0.45 and RE of 28% were achieved.The addition of an adequate amount of crosslinking agent imparted starch succinate water absorbency. 相似文献
18.
Effects of ammonium exchange and Si/Al ratio on the conversion of methanol to propylene over a novel and large partical size ZSM-5
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One type of ZSM-5 zeolite with large partical size was prepared and characterized by XRD, SEM, N2 adsorption-desorption, XRF, Py-IR and NH3-TPD techniques. Effects of ammonium exchange and SiO2/Al2O3 molar ratios on the reaction of methanol to propylene (MTP) over Na-ZSM-5 and H-ZSM-5 zeolites have been studied in a fixed-bed flow reactor under the operating conditions of T = 500 °C, P = 1 atm, and WHSV = 6 h-1. Ammonium exchange led to a rapid decrease in Na content for Na-ZSM-5 zeolite. The reaction results indicated that Na-ZSM-5 and H-ZSM-5 with different SiO2/Al2O3 molar ratios all exhibited high activity for methanol conversion. Ammonium exchange and the decreased SiO2/Al2O3 molar ratio of ZSM-5 zeolite led to an increase both in strong acid sites and weak acid sites. Na-ZSM-5 with high SiO2/Al2O3 molar ratio was favorable for the formation of propylene. The highest propylene selectivity (45.9%) was obtained over Na-ZSM-5 zeolite catalyst with SiO2/Al2O3 molar ratio of 220. 相似文献
19.
The synthesis of formic acid from carbon dioxide and hydrogen using a silica immobilized ruthenium catalyst as precursor has been studied in different reaction conditions. The results revealed that the TOF (turn over frequency) of HCOOH achieved 1481.5 h^-1 on immobilized ruthenium catalyst near the critical pressure point of CO2 with H2 pressure of 4.0 MPa, reaction temperature of 80℃ and PPh3/Ru molar ratio of 6:1. The reaction activity of immobilized catalyst was higher than that of homogeneous catalyst, and the immobilized catalyst also offered the practical advantages such as easy separation and reuse. 相似文献
20.
《Journal of Energy Chemistry》2017,26(3):488-493
In terms of the reaction of CO_2 reduction to CO with hydrogen, CO_2 conversion is very low at low temperature due to the limitation of thermodynamic equilibrium(TE). To overcome this limitation, plasma catalytic reduction of CO_2 to CO in a catalyst-filled dielectric barrier discharge(DBD) reactor is studied. An enhanced effect of plasma on the reaction over Au/CeO_2 catalysts is observed. For both the conventionally catalytic(CC) and plasma catalytic(PC, Pin= 15 W) reactions under conditions of 400 °C, H_2/CO_2= 1,200 SCCM, GHSV = 12,000 mL·g~(-1)cat·h~(-1), CO_2 conversions over Au/CeO_2 reach 15.4% and 25.5% due to the presence of Au, respectively, however, those over CeO_2 are extremely low and negligible. Moreover,CO_2 conversion over Au/CeO_2 in the PC reaction exceeds 22.4% of the TE conversion. Surface intermediate species formed on the catalyst samples during the reactions are determined by in-situ temperatureprogrammed decomposition(TPD) technique. Interestingly, it disclosed that in the PC reaction, the formation of formate intermediate is enhanced by plasma, and the acceleration by plasma in the decomposition of formate species is much greater than that in the formation of formate species on Au/CeO_2. Enhancement factor is introduced to quantify the enhanced effect of plasma. Lower reactor temperature, higher gas hourly space velocity(GHSV), and lower molar ratio of H_2/CO_2 would be associated with larger enhancement factor. 相似文献