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1.
A Ni-La/SiO2 catalyst was prepared through the incipient wetness impregnation method and tested in the oxidative dehydrogenation of ethane (ODHE) with CO2. The fresh and used catalysts were characterized by XRD and SEM techniques. The Ni-La/SiO2 catalyst exhibited catalytic activity for the oxidative dehydrogenation of ethane, but with low ethylene selectivity in the absence of methane. The selectivity to ethylene increased with increasing molar ratio of methane in the feed. The carbon deposited on the catalyst surface in the sole ODHE with CO2 was mainly inert carbon, while much more filamentous carbon was formed in the presence of methane. The filamentous carbon was easy to be removed by CO2, which might play a role in improving the conversion of ethane to ethylene. The introduction of methane might affect the equilibrium of the CO2 reforming of ethane and the ODHE with CO2. As a consequence, the synthesis gas produced from CO2 reforming of methane partly inhibited the reaction of ethane and promoted the ODHE with CO2, thus increasing the selectivity of ethylene. 相似文献
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3.
Adsorptive Separation of Acetylene from Light Hydrocarbons by Mesoporous Iron Trimesate MIL‐100(Fe)
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Sukyung Lee Kyoung Ho Cho Dr. Young Kyu Hwang Prof. Dr. Marco Daturi Prof. Chul‐Ho Jun Prof. Dr. Rajamani Krishna Prof. Dr. Jong‐San Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18431-18438
A reducible metal–organic framework (MOF), iron(III) trimesate, denoted as MIL‐100(Fe), was investigated for the separation and purification of methane/ethane/ethylene/acetylene and an acetylene/CO2 mixtures by using sorption isotherms, breakthrough experiments, ideal adsorbed solution theory (IAST) calculations, and IR spectroscopic analysis. The MIL‐100(Fe) showed high adsorption selectivity not only for acetylene and ethylene over methane and ethane, but also for acetylene over CO2. The separation and purification of acetylene over ethylene was also possible for MIL‐100(Fe) activated at 423 K. According to the data obtained from operando IR spectroscopy, the unsaturated FeIII sites and surface OH groups are mainly responsible for the successful separation of the acetylene/ethylene mixture, whereas the unsaturated FeII sites have a detrimental effect on both separation and purification. The potential of MIL‐100(Fe) for the separation of a mixture of C2H2/CO2 was also examined by using the IAST calculations and transient breakthrough simulations. Comparing the IAST selectivity calculations of C2H2/CO2 for four MOFs selected from the literature, the selectivity with MIL‐100(Fe) was higher than those of CuBTC, ZJU‐60a, and PCP‐33, but lower than that of HOF‐3. 相似文献
4.
Catalytic performance of silica-supported chromium oxide catalysts in ethane dehydrogenation with carbon dioxide 总被引:1,自引:0,他引:1
The oxidative dehydrogenation of ethane into ethylene by CO2 over a series of silica-supported chromium oxide catalysts was investigated. The results showed that the catalysts were effective for the reaction and CO2 in the feed promoted the catalytic activity. The 5%Cr/SiO2 catalyst exhibited the excellent performance with 30.7% ethane conversion and 96.5% ethylene selectivity at 700oC. ESR and UV-DRS were used to probe the active sites and the species with high valent states (Cr5+ and/or Cr6+) were found to be important for the reaction. 相似文献
5.
Vasant R. Choudhary Kartick C. Mondal Shafeek A. R. Mulla 《Journal of Chemical Sciences》2006,118(3):261-267
Influence of the presence of CO2, which is a mild oxidant, on the performance of the thermal cracking of ethane to ethylene in the absence or presence of
limited O2 at different temperatures (750–900‡C), space velocities (1500–9000 h-1) and CO2/C2H6 and O2/C2H6 mole ratios (0–2.0 and 0–0.3 respectively) has been investigated. In both the presence and absence of limited O2, ethane conversion increases markedly because of the presence of CO2, indicating its beneficial effect on the ethane to ethylene cracking. The increased ethane conversion is, however, not due
to the oxidation of ethane to ethylene by CO2; the formation of carbon monoxide in the presence of CO2 is found to be very small. It is most probably due to the activation of ethane in the presence of CO2. 相似文献
6.
Dr. Winyoo Sangthong Prof. Dr. Michael Probst Prof. Dr. Jumras Limtrakul 《Chemphyschem》2014,15(3):514-520
Finding novel catalysts for the direct conversion of CO2 to fuels and chemicals is a primary goal in energy and environmental research. In this work, density functional theory (DFT) is used to study possible reaction mechanisms for the conversion of CO2 and C2H6 to propanoic acid over a gold‐exchanged MCM‐22 zeolite catalyst. The reaction begins with the activation of ethane to produce a gold ethyl hydride intermediate. Hydrogen transfers to the framework oxygen leads then to gold ethyl adsorbed on the Brønsted‐acid site. The energy barriers for these steps of ethane activation are 9.3 and 16.3 kcal mol?1, respectively. Two mechanisms of propanoic acid formation are investigated. In the first one, the insertion of CO2 into the Au?H bond of the first intermediate yields gold carboxyl ethyl as subsequent intermediate. This is then converted to propanoic acid by forming the relevant C?C bond. The activation energy of the rate‐determining step of this pathway is 48.2 kcal mol?1. In the second mechanism, CO2 interacts with gold ethyl adsorbed on the Brønsted‐acid site. Propanoic acid is formed via protonation of CO2 by the Brønsted acid and the simultaneous formation of a bond between CO2 and the ethyl group. The activation energy there is 44.2 kcal mol?1, favoring this second pathway at least at low temperatures. Gold‐exchanged MCM‐22 zeolite can therefore, at least in principle, be used as the catalyst for producing propanoic acid from CO2 and ethane. 相似文献
7.
Jiajun Wang Shyam Kattel Christopher J. Hawxhurst Ji Hoon Lee Brian M. Tackett Kuan Chang Ning Rui Chang‐Jun Liu Jingguang G. Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6337-6341
Electrochemical CO2 reduction reaction (CO2RR) with renewable electricity is a potentially sustainable method to reduce CO2 emissions. Palladium supported on cost‐effective transition‐metal carbides (TMCs) are studied to reduce the Pd usage and tune the activity and selectivity of the CO2RR to produce synthesis gas, using a combined approach of studying thin films and practical powder catalysts, in situ characterization, and density functional theory (DFT) calculations. Notably, Pd/TaC exhibits higher CO2RR activity, stability and CO Faradaic efficiency than those of commercial Pd/C while significantly reducing the Pd loading. In situ measurements confirm the transformation of Pd into hydride (PdH) under the CO2RR environment. DFT calculations reveal that the TMC substrates modify the binding energies of key intermediates on supported PdH. This work suggests the prospect of using TMCs as low‐cost and stable substrates to support and modify Pd for enhanced CO2RR activity. 相似文献
8.
Structural Optimization of Interpenetrated Pillared‐Layer Coordination Polymers for Ethylene/Ethane Separation
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Keisuke Kishida Dr. Satoshi Horike Yoshihiro Watanabe Mina Tahara Yasutaka Inubushi Prof. Susumu Kitagawa 《化学:亚洲杂志》2014,9(6):1643-1647
With the goal of achieving effective ethylene/ethane separation, we evaluated the gas sorption properties of four pillared‐layer‐type porous coordination polymers with double interpenetration, [Zn2(tp)2(bpy)]n ( 1 ), [Zn2(fm)2(bpe)]n ( 2 ), [Zn2(fm)2(bpa)]n ( 3 ), and [Zn2(fm)2(bpy)]n ( 4 ) (tp=terephthalate, bpy=4,4′‐bipyridyl, fm=fumarate, bpe=1,2‐di(4‐pyridyl)ethylene and bpa=1,2‐di(4‐pyridyl)ethane). It was found that 4 , which contains the narrowest pores of all of these compounds, exhibited ethylene‐selective sorption profiles. The ethylene selectivity of 4 was estimated to be 4.6 at 298 K based on breakthrough experiments using ethylene/ethane gas mixtures. In addition, 4 exhibited a good regeneration ability compared with a conventional porous material. 相似文献
9.
The catalytic stability of LiCl/MnOx/PC catalyst have been investigated, the deactivation mechanism was discussed. The experimental results show that ethane conversion decreases and ethylene selectivity keeps about 90% as reaction time increases. The main deactivation reasons of LiCl/MnOx/PC catalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transition of active species Mn2O3 to MnO species and the loss of active component Cl in catalyst. Instead of ethane with FCC tailed‐gas, the stability of LiCl/MnOx/PC catalyst has been largely improved. 相似文献
10.
Molly Meng‐Jung Li Hanbo Zou Jianwei Zheng Tai‐Sing Wu Ting‐Shan Chan Yun‐Liang Soo Xin‐Ping Wu Xue‐Qing Gong Tianyi Chen Kanak Roy Georg Held Shik Chi Edman Tsang 《Angewandte Chemie (International ed. in English)》2020,59(37):16039-16046
There is increasing interest in capturing H2 generated from renewables with CO2 to produce methanol. However, renewable hydrogen production is expensive and in limited quantity compared to CO2. Excess CO2 and limited H2 in the feedstock gas is not favorable for CO2 hydrogenation to methanol, causing low activity and poor methanol selectivity. Now, a class of Rh‐In catalysts with optimal adsorption properties to the intermediates of methanol production is presented. The Rh‐In catalyst can effectively catalyze methanol synthesis but inhibit the reverse water‐gas shift reaction under H2‐deficient gas flow and shows the best competitive methanol productivity under industrially applicable conditions in comparison with reported values. This work demonstrates a strong potential of Rh‐In bimetallic composition, from which a convenient methanol synthesis based on flexible feedstock compositions (such as H2/CO2 from biomass derivatives) with lower energy cost can be established. 相似文献
11.
One vision of clean energy for the future is to produce hydrogen from coal in an ultra-clean plant. The conventional route
consists of reacting the coal gasification product (after removal of trace impurities) with steam in a water gas shift (WGS)
reactor to convert CO to CO2 and H2, followed by purification of the effluent gas in a pressure swing adsorption (PSA) unit to produce a high purity hydrogen
product. PSA processes can also be designed to produce a CO2 by-product at ambient pressure. This work proposes a novel concept called “Thermal Swing Sorption Enhanced Reaction (TSSER)”
which simultaneously carries out the WGS reaction and the removal of CO2 from the reaction zone by using a CO2 chemisorbent in a single unit operation. The concept directly produces a fuel-cell grade H2 and compressed CO2 as a by-product gas. Removal of CO2 from the reaction zone circumvents the equilibrium limitations of the reversible WGS reaction and enhances its forward rate
of reaction. Recently measured sorption-desorption characteristics of two novel, reversible CO2 chemisorbents (K2CO3 promoted hydrotalcite and Na2O promoted alumina) are reviewed and the simulated performance of the proposed TSSER concept using the promoted hydrotalcite
as the chemisorbent is reported. 相似文献
12.
Dr. Lin‐Hua Xie Prof. Myunghyun Paik Suh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(35):11590-11597
A new porous organic polymer, SNU‐C1 , incorporating two different CO2‐attracting groups, namely, carboxy and triazole groups, has been synthesized. By activating SNU‐C1 with two different methods, vacuum drying and supercritical‐CO2 treatment, the guest‐free phases, SNU‐C1‐va and SNU‐C1‐sca , respectively, were obtained. Brunauer–Emmett–Teller (BET) surface areas of SNU‐C1‐va and SNU‐C1‐sca are 595 and 830 m2g?1, respectively, as estimated by the N2‐adsorption isotherms at 77 K. At 298 K and 1 atm, SNU‐C1‐va and SNU‐C1‐sca show high CO2 uptakes, 2.31 mmol g?1 and 3.14 mmol g?1, respectively, the high level being due to the presence of abundant polar groups (carboxy and triazole) exposed on the pore surfaces. Five separation parameters for flue gas and landfill gas in vacuum‐swing adsorption were calculated from single‐component gas‐sorption isotherms by using the ideal adsorbed solution theory (IAST). The data reveal excellent CO2‐separation abilities of SNU‐C1‐va and SNU‐C1‐sca , namely high CO2‐uptake capacity, high selectivity, and high regenerability. The gas‐cycling experiments for the materials and the water‐treated samples, experiments that involved treating the samples with a CO2‐N2 gas mixture (15:85, v/v) followed by a pure N2 purge, further verified the high regenerability and water stability. The results suggest that these materials have great potential applications in CO2 separation. 相似文献
13.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(3):814-818
The electrocatalytic conversion of CO2 to value‐added hydrocarbons is receiving significant attention as a promising way to close the broken carbon‐cycle. While most metal catalysts produce C1 species, such as carbon monoxide and formate, the production of various hydrocarbons and alcohols comprising more than two carbons has been achieved using copper (Cu)‐based catalysts only. Methods for producing specific C2 reduction outcomes with high selectivity, however, are not available thus far. Herein, the morphological effect of a Cu mesopore electrode on the selective production of C2 products, ethylene or ethane, is presented. Cu mesopore electrodes with precisely controlled pore widths and depths were prepared by using a thermal deposition process on anodized aluminum oxide. With this simple synthesis method, we demonstrated that C2 chemical selectivity can be tuned by systematically altering the morphology. Supported by computational simulations, we proved that nanomorphology can change the local pH and, additionally, retention time of key intermediates by confining the chemicals inside the pores. 相似文献
14.
Yuxiang Chen Ke Gong Feng Jiao Xiulian Pan Guangjin Hou Rui Si Xinhe Bao 《Angewandte Chemie (International ed. in English)》2020,59(16):6529-6534
Despite significant progress achieved in Fischer–Tropsch synthesis (FTS) technology, control of product selectivity remains a challenge in syngas conversion. Herein, we demonstrate that Zn2+‐ion exchanged ZSM‐5 zeolite steers syngas conversion selectively to ethane with its selectivity reaching as high as 86 % among hydrocarbons (excluding CO2) at 20 % CO conversion. NMR spectroscopy, X‐ray absorption spectroscopy, and X‐ray fluorescence indicate that this is likely attributed to the highly dispersed Zn sites grafted on ZSM‐5. Quasi‐in‐situ solid‐state NMR, obtained by quenching the reaction in liquid N2, detects C2 species such as acetyl (‐COCH3) bonding with an oxygen, ethyl (‐CH2CH3) bonding with a Zn site, and epoxyethane molecules adsorbing on a Zn site and a Brønsted acid site of the catalyst, respectively. These species could provide insight into C?C bond formation during ethane formation. Interestingly, this selective reaction pathway toward ethane appears to be general because a series of other Zn2+‐ion exchanged aluminosilicate zeolites with different topologies (for example, SSZ‐13, MCM‐22, and ZSM‐12) all give ethane predominantly. By contrast, a physical mixture of ZnO‐ZSM‐5 favors formation of hydrocarbons beyond C3+. These results provide an important guide for tuning the product selectivity in syngas conversion. 相似文献
15.
Satej S. Deshmukh Shahaji R. Gaikwad Rajesh G. Gonnade Satish P. Pandole Samir H. Chikkali 《化学:亚洲杂志》2020,15(3):398-405
Designing co‐catalyst‐free late transition metal complexes for ethylene polymerization is a challenging task at the interface of organometallic and polymer chemistry. Herein, a set of new, co‐catalyst‐free, single‐component catalytic systems for ethylene polymerization have been unraveled. Treatment of anthranilic acid with various aldehydes produced four iminocarboxylate ligands ( L1 – L4 ) in very good to excellent yield (75–92 %). The existence of 2‐((2‐methoxybenzylidene)amino) benzoic acid ( L1 ) has been unambiguously demonstrated using NMR spectroscopy, MS and single‐crystal X‐ray diffraction. A neutral Pd‐iminocarboxylate complex [{N O}PdMe(L1)] (N O=κ2‐N,O‐ArCHNC6H4CO2 with Ar=2‐MeOC6H4) C1 was prepared by treating stoichiometric amount of L1.Na with palladium precursor. The identity of C1 was confirmed by 1–2D NMR spectroscopy and single‐crystal X‐ray diffraction studies. Along the same lines, palladium complexes C2 – C4 were prepared from ligands L2 – L4 respectively. In‐situ high‐pressure NMR investigations revealed that these Pd complexes are amenable to ethylene insertion and undergo facile β‐H elimination to produce propylene. These palladium complexes were then evaluated in ethylene polymerization reaction and various reaction parameters were screened. When C1 – C4 were exposed to ethylene pressures of 10–50 bar, formation of low‐molecular‐weight polyethylene was observed. 相似文献
16.
Controllable Hydrocarbon Formation from the Electrochemical Reduction of CO2 over Cu Nanowire Arrays
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Ming Ma Dr. Kristina Djanashvili Dr. Wilson A. Smith 《Angewandte Chemie (International ed. in English)》2016,55(23):6680-6684
In this work, the effect of Cu nanowire morphology on the selective electrocatalytic reduction of CO2 is presented. Cu nanowire arrays were prepared through a two‐step synthesis of Cu(OH)2 and CuO nanowire arrays on Cu foil substrates and a subsequent electrochemical reduction of the CuO nanowire arrays to Cu nanowire arrays. By this simple synthesis method, Cu nanowire array electrodes with different length and density were able to be controllably synthesized. We show that the selectivity for hydrocarbons (ethylene, n‐propanol, ethane, and ethanol) on Cu nanowire array electrodes at a fixed potential can be tuned by systematically altering the Cu nanowire length and density. The nanowire morphology effect is linked to the increased local pH in the Cu nanowire arrays and a reaction scheme detailing the local pH‐induced formation of C2 products is also presented by a preferred CO dimerization pathway. 相似文献
17.
Anthony Vasileff Dr. Yanping Zhu Xing Zhi Dr. Yongqiang Zhao Dr. Lei Ge Prof. Hao Ming Chen Dr. Yao Zheng Prof. Shi-Zhang Qiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19817-19821
Electrochemical conversion of CO2 into ethane is seldom observed because of the generally higher selectivity towards methane, ethylene, and ethanol. Consequently, little experimental evidence for its reaction mechanism exists and thus remains largely unknown. Now, by combining electrochemistry with in situ X-ray absorption fine-structure and in situ Raman techniques, iodide-derived copper (ID-Cu) and oxide-derived copper (OD-Cu) systems were studied to obtain a deeper understanding of the CO2 to ethane mechanism. With trace iodine species on the surface and positively charged Cu species, production of ethane is significantly more favored on ID-Cu compared to OD-Cu, with higher selectivity and faster kinetics. For the first time, it is experimentally found that the formation of ethane follows the same pathway to ethylene and ethanol, and better stabilization of the late stage ethoxy intermediate can steer the reaction to ethane over ethanol. 相似文献
18.
Satoshi Kaneco Kenji Iiba Kiyohisa Ohta Takayuki Mizuno 《Journal of Solid State Electrochemistry》1999,3(7-8):424-428
The electrochemical reduction of CO2 at a Cu electrode was investigated in a methanol-based electrolyte using such potassium supporting salts as CH3COOK, KBr, KI and KSCN at extremely low temperature (−30 °C). The main products obtained from CO2 by the electrochemical reduction were methane, ethylene, ethane, carbon monoxide and formic acid. The maximum Faradaic efficiency
of ethylene was 19.9% in KI/methanol-based catholyte at −3.0 V vs. Ag/AgCl saturated KCl. The best methane formation (27.0%)
was obtained in CH3COOK/methanol electrolyte at −3.0 V. In the system containing a potassium halide, the efficiency of hydrogen formation, being
a competitive reaction against CO2 reduction, was suppressed to less than 8.1%. The product selectivity of the electrochemical reduction of CO2 in methanol was greatly affected by the anionic species. This research can contribute to the large-scale manufacturing of
useful organic products from readily available and cheap raw materials: CO2-saturated methanol from industrial absorbers (the Rectisol process).
Received: 11 November 1998 / Accepted: 1 February 1999 相似文献
19.
Yumeng Liu Dong Tian Akash N. Biswas Zhenhua Xie Sooyeon Hwang Ji Hoon Lee Hong Meng Jingguang G. Chen 《Angewandte Chemie (International ed. in English)》2020,59(28):11345-11348
The electrochemical carbon dioxide reduction reaction (CO2RR) to produce synthesis gas (syngas) with tunable CO/H2 ratios has been studied by supporting Pd catalysts on transition metal nitride (TMN) substrates. Combining experimental measurements and density functional theory (DFT) calculations, Pd‐modified niobium nitride (Pd/NbN) is found to generate much higher CO and H2 partial current densities and greater CO Faradaic efficiency than Pd‐modified vanadium nitride (Pd/VN) and commercial Pd/C catalysts. In‐situ X‐ray diffraction identifies the formation of PdH in Pd/NbN and Pd/C under CO2RR conditions, whereas the Pd in Pd/VN is not fully transformed into the active PdH phase. DFT calculations show that the stabilized *HOCO and weakened *CO intermediates on PdH/NbN are critical to achieving higher CO2RR activity. This work suggests that NbN is a promising substrate to modify Pd, resulting in an enhanced electrochemical conversion of CO2 to syngas with a potential reduction in precious metal loading. 相似文献
20.
The poly(ethylene oxide) (PEO) was introduced by the cross-linking method in the commercial Matrimid 5218. The two kinds of membranes were prepared from the Matrimid 5218 and the cross-linkers poly(propylene glycol) block poly(ethylene glycol) block poly(propylene glycol) diamine (PPG/PEG/PPGDA) with different molecular weights. The cross-linking reaction process was monitored by FTIR. The cross-linked Matrimid 5218 membranes display excellent CO2 permeability and CO2/light gas selectivity. The effects of cross-linkers with different molecular weights on gel content, thermal properties and H2, CO2, N2 and CH4 gas transport properties were reported. The effect of temperature on gas transport properties was also reported, and the permeabilities of these materials as a function of temperature were compared with other gas membrane materials. 相似文献