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Computational chemistry is used to explore a mechanism for CO hydrogenation to methane on iron carbides. As CO dissociation is endothermic on carbon terminated Fe5C2 (100) cuts, we explore a path starting with the hydrogenation of the surface, which liberates iron 4-fold sites for adsorption and dissociation of CO. The reaction cycle to methane resembles the Mars-van Krevelen mechanism for oxidation reactions. 相似文献
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Deuterated organic compounds can be prepared efficiently and cost effectively by the direct exchange of a hydrogen atom by a deuterium atom on a carbon center rather than classical synthetic procedures. H/D exchange is achieved at allylic positions of alkenes catalyzed by alkene isomerization catalyst 1. An outstanding degree of deuteration is achieved at positions accessible by isomerization in homogeneous and biphasic reaction settings. 相似文献
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We have developed a ReaxFF reactive force field to describe hydrogen adsorption and dissociation on iron and iron carbide surfaces relevant for simulation of Fischer?CTropsch (FT) synthesis on iron catalysts. This force field enables large system (>>1000 atoms) simulations of hydrogen related reactions with iron. The ReaxFF force field parameters are trained against a substantial amount of structural and energetic data including the equations of state and heats of formation of iron and iron carbide related materials, as well as hydrogen interaction with iron surfaces and different phases of bulk iron. We have validated the accuracy and applicability of ReaxFF force field by carrying out molecular dynamics simulations of hydrogen adsorption, dissociation and recombination on iron and iron carbide surfaces. The barriers and reaction energies for molecular dissociation on these two types of surfaces have been compared and the effect of subsurface carbon on hydrogen interaction with iron surface is evaluated. We found that existence of carbon atoms at subsurface iron sites tends to increase the hydrogen dissociation energy barrier on the surface, and also makes the corresponding hydrogen dissociative state relatively more stable compared to that on bare iron. These properties of iron carbide will affect the dissociation rate of H2 and will retain more surface hydride species, thus influencing the dynamics of the FT synthesis process. 相似文献
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采用超声预处理活性炭,并用N_2物理吸附、X射线能谱仪(EDS)、透射电镜(TEM)、和场发射扫描电镜(FE-SEM)等表征手段,研究了超声预处理条件对活性炭表面结构、化学成分及表面形貌以及所负载钌基氨合成催化剂性能的影响。研究结果表明,超声预处理活性炭,可有效降低活性炭表面灰分和不稳定含氧基团的含量,从而提高所负载催化剂的活性。在实验范围内,当超声频率为39.0 kHz,功率为100w时,在10 000 h~(-1),10.0 MPa和400℃的反应条件下,钌基催化剂的反应速率达到了97.6 mmol/(g·h)。 相似文献
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The effect of hydrogen treatment (400 °C/1 h) on the catalytic properties toward H2O2 decomposition of iron oxide based materials dispersed over activated carbon were investigated. Two different supports were evaluated: a commercial activated carbon (ACM) and an activated carbon produced from spent coffee grounds (ACR). The catalysts were characterized using XRD, SEM, N2-sorption, XPS and TPR analysis. The main results suggest the formation of composites with high surface area (>800 m2 g?1) and the hydrogen treatment resulted in a great increase in the catalytic activity, probably as a function of the reduced iron species (Fe2+ and Fe0) formed with the treatment. Moreover, the catalyst prepared with ACR showed to be more active than that prepared from ACM. 相似文献
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Iuliia Romanenko Sbastien Norsic Laurent Veyre Reine Sayah Franck D'Agosto Jean Raynaud Christophe Boisson Emmanuel Lacte Chlo Thieuleux 《Advanced Synthesis \u0026amp; Catalysis》2016,358(14):2317-2323
The multistep synthesis of a polyethylene‐supported iridium(III)‐(N‐heterocyclic carbene) hydrogen/deuterium exchange catalyst was performed starting from an iodo‐polyethylene obtained via catalyzed polyethylene chain growth (CCG) on magnesium. Unique thermomorphic polyethylene properties give the possibility to perform catalytic hydrogen/deuterium exchange reactions at 100 °C in the homogeneous phase with simple catalyst separation as a precipitate at room temperature. The catalytic activity of the polymer‐supported catalyst was compared with that of its monomeric analogue. The catalytic studies showed that the supported catalyst exhibits similar profiles and turnover numbers as homogeneous counterparts without deactivation.
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采用沉积-沉淀法制备了4% Pd/C催化剂(Pd质量分数4%),分别以硝酸、盐酸、双氧水和氨水4种溶剂对Pd/C的载体活性炭进行改性,并对载体活性炭的比表面积和孔结构、零电荷点(PZC)以及活性组分Pd的分散度进行了表征,研究了活性炭改性对Pd催化剂在松香歧化反应中催化性能的影响。结果表明:经氨水改性后活性炭比表面积孔径增大且活性炭PZC值升高,有利于活性组分Pd在载体表面的分散,以氨水改性活性炭为载体制备得到的Pd/C催化剂活性最高,在催化剂投料量为0.03%,280℃反应2 h条件下,脱氢枞酸质量分数高达81.7%。 相似文献
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Dr. Liangjie Tang Stephen J. Coales Jeffrey A. Morrow Dr. Tim Edmunds Dr. Yoshitomo Hamuro 《Chembiochem : a European journal of chemical biology》2012,13(15):2243-2250
An asparagine‐to‐serine substitution at residue 370 (N370S) in glucocerebrosidase (GCase) is the most prevalent mutation leading to Gaucher's disease, the most common lysosomal storage disorder. Two types of hydrogen/deuterium exchange experiment coupled with proteolysis and liquid chromatography–mass spectrometry (HDX–MS) were used to investigate the dynamic properties and unfolding stability of wt, R495H, and N370S GCases in the presence and absence of ligands. R495H GCase is used for enzyme replacement therapy and is considered to be a wt surrogate, whereas N370S is the most prevalent mutation leading to Gaucher's disease. Time‐course HDX experiments of the GCases were performed under near‐physiological conditions to detect the protein's local unfolding motions at a submolecular level. In guanidine‐titration experiments, HDX reactions were performed with various concentrations of a chemical denaturant to provide the global stability of the proteins. The two types of experiment showed that all three purified GCases, wt, R495H, and N370S, have virtually identical local unfolding motions and global stabilities in solution. Combined with previous X‐ray crystallographic studies, which showed indistinguishable backbone conformations for N370S and R495H GCase mutants and very similar melting temperatures for the wt, R495H, and N370S mutants, all three GCases are likely to have virtually identical structural and dynamic properties in solution. The guanidine‐titration experiments revealed that the pharmacological chaperone, isofagomine (IFG), interacts more weakly with the N370S mutant than with the R495H GCase; this is consistent with the higher IC50 value of IFG against N370S than against R495H. The time‐course experiments showed that IFG restricts the local unfolding motions of N370S in the same way as those of R495H when the ligand saturates the proteins. 相似文献
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制备了活性炭固载溴化1-(2-胺乙基氢溴酸)-3-甲基咪唑翁盐离子液体催化剂,并用TG和XPS对催化剂进行了表征。将该催化剂首次用于Knoevenagel缩合反应,结果表明活性炭固载离子液体催化剂具有良好的催化活性和稳定性,同时克服了均相催化剂难以分离的不足。 相似文献
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在1023 K温度下用热重法结合XRD和EDX分析研究了70%H2-30%CH4混合气体还原铁矿石制备碳化铁的过程,测定了原矿和还原中间产物的微孔分布. 结果表明,相同反应条件下微观结构不同的铁矿石其还原速率和碳化速率有较大差别,巴西块矿、澳大利亚块矿及南非球团矿在50 min内都可以全部还原,此后生成碳化铁;而南非块矿则需90 min才能基本还原,此后没有碳化铁生成. 疏松多孔的铁矿石较致密铁矿石的还原速率快,生成的还原铁结构疏松,有利于碳化反应的进行. 铁矿石还原后,0.5~3.5 nm微孔孔容积率约提高2倍,分布规律与原矿石相似,3.5~13 nm的微孔孔容积提高显著,这些对还原速率和碳化铁的生成反应有较大影响. 相似文献
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采用高温氢气对不同活性炭进行处理,并分别采用比表面分析仪(BET)、红外光谱(IR)、氩气-程序升温脱附实验(Ar-TPD)和热重分析(TGA)对高温氢气处理前后的活性炭进行表征.结果表明,高温氢气处理对活性炭的孔结构和比表面影响较小,高温氢气处理后活性炭表面含氧官能团含量降低.以高温氢气处理后的活性炭为载体制备钯炭催化剂,催化剂上的钯的分散度降低,在粗对苯二甲酸精制反应中的初活性下降. 相似文献
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通过理论分析和实验,提出了在工业条件下原料气中氢氮分压变化(包括氢氮比、惰性气体含量、合成压力变化)与熔铁催化剂氨合成率变化之间的关系式。利用该式所得的计算值与实验值十分吻合。 相似文献
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Ajit Sharma Doan Van Thuan Thanh-Dong Pham Mai Hung Thanh Tung Nguyen Thi Thanh Truc Dai-Viet N. Vo 《化学工程与技术》2020,43(4):752-761
FeO-doped TiO2 nanoparticle photocatalysts were immobilized onto the surface of fibrous activated carbon (ACF) via a sol-gel process. As an adsorbent and photocatalyst, FeO-TiO2 on immobilized ACFs (FeO-TiO2/ACF) greatly improved the photocatalysis rate of hydrogen production as compared with pure TiO2 and ACF-TiO2 under UV irradiation and visible light. The addition of ACFs surface significantly reduced the photogenerated pairs of electrons-hole recombination, thereby promoting the photocatalysis action of doped photo-metal oxides of FeO-TiO2. Co-doping of FeO onto the lattice of the TiO2 approach can improve the absorption activity of visible light through photo-metal oxide of TiO2 and further enhance hydrogen production under visible light. The photocatalytic fabrics (FeO-TiO2/ACF) were effortlessly split out from the experimental solution for re-utilization and exhibited high stability even after five complete regeneration cycles. 相似文献
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Sunny Kai San Tse Peng Xue Zhenyang Lin Guochen Jia 《Advanced Synthesis \u0026amp; Catalysis》2010,352(9):1512-1522
The catalytic properties of several ruthenium, osmium and rhodium hydride complexes for hydrogen/deuterium (H/D) exchange between olefins and deuterium oxide (D2O) were investigated. The most effective catalytic precursor was found to be the carbonylchlorohydridotris(triphenylphosphine)ruthenium(II) complex. Through H/D exchange between metal hydride and D2O, and reversible olefin insertion into an Ru H(D) bond, protons attached to olefinic carbons and alkyl chains of olefins can all undergo H/D exchange with D2O. The catalytic reactions can be used to deuterate both terminal and internal olefins, for example, styrene, stilbene and cyclooctene. 相似文献