提高Rh-Mn/SiO_2催化剂合成乙醇性能的途径研究

通过实验分别研究了浸渍顺序、Mn负载量以及工况条件对Rh-Mn/SiO2催化剂上CO加氢合成乙醇反应的影响,并采用程序升温还原(TPR)技术对催化剂进行表征。结果表明:同时浸渍铑锰的催化剂的C2含氧化合物的时空产率达到255.8g/(kg·h),乙醇的选择性为15.39%,均高于分步浸渍的催化剂;Mn负载量影响Rh-Mn的相互作用,实验发现当催化剂w(Mn)为1.5%时,乙醇的选择性可升高到18.09%,同时可以抑制甲烷的生成。研究确定了Rh-Mn/SiO2催化CO加氢合成乙醇的最优工艺条件。     

催化裂解中甲烷选择性的影响因素

针对催化裂解反应中甲烷的生成机理及其选择性的影响因素,以C₈烷烃为模型化合物,研究了反应温度、辛烷异构体及ZSM-5、MPZ和拟薄水铝石3种催化材料对催化裂解过程甲烷选择性的影响。结果表明：随着反应温度升高,烷烃分子发生质子化裂化过程中能够生成甲烷的路径发生概率提高;原料的分子结构是决定其催化裂解甲烷选择性的本质因素,甲烷选择性随原料分子烷基侧链数目的增加而增大,弱化正碳离子的异构化反应可抑制甲烷过度生成;催化材料的结构特征和酸性是影响甲烷选择性的关键因素,较大的孔径和比表面积在促进内扩散的同时提供了更多的活性位点,能有效提高反应物分子的转化率,但对甲烷选择性影响不显著,而Lewis酸则对甲烷的生成起到重要的催化作用。     

CO_2催化转化研究新进展

综述了近年来由二氧化碳催化加氢合成甲烷、甲醇及低碳烯烃 ,用二氧化碳选择性催化氧化制合成气 ,催化共聚生成高分子材料方面的新进展。     

CO2催化转化研究新进展

综述了近年来由二氧化碳催化加氢合成甲烷、甲醇及低碳烯烃,用二氧化碳选择性催化氧化制合成气,催化共聚生成高分子材料方面的新进展。     

OC2催化转化研究新进展

综述了近年来由二氧化碳催化加氢合成甲烷、甲醇及低碳烯烃,用二氧化碳选择性催化氧化制合成气,催化共聚生成高分子材料方面的新进展。     

含膦及含膦氮配体Ni、Co、Pd催化剂的合成及对乙醇羰基化的催化活性

合成了含膦及含膦氮配体，并用它合成了一系列Ｎｉ、Ｃｏ、Ｐｄ化合物，对乙醇羰基化合成丙酸乙酯的催化活性进行了评价，其催化活性顺序：Ｎｉ～Ｃｏ＜Ｐｄ，含ＰＡＰ配体的络合物对乙醇羰基化生成丙酸乙酯的选择性高于ＰＰｈ＿３及ＰＮＰ。     

天然气中甲烷和乙烷直接转化制乙烯

天然气中的甲烷和乙烷可以同时在Ｎａ２ＷＯ４－Ｍｎ／ＳｉＯ２催化剂上得到活化生成乙烯。在甲烷转化率为２０％时，原料甲烷氧化偶联反应生成Ｃ２＋的选择性为～８０％，原料乙烷反应的转化率为～８５％，选择性为～７０％。     

石脑油催化裂解生成甲烷的影响因素探析

对比分析了直馏石脑油热裂解和催化裂解过程中甲烷产率的差异及其根源,探索了工艺参数、催化剂活性和烃类分子结构对石脑油催化裂解反应中甲烷的产率和选择性的影响。结果表明：甲烷主要来自于石脑油的催化裂解反应,催化剂上的较强Br?nsted酸中心是甲烷生成的活性中心;链烷烃催化裂解更易于生成甲烷;反应温度和油剂接触时间是影响甲烷生成的关键因素,对此提出采用适宜反应温度和大剂油比,在保证原料必要的转化深度的同时,开发超短接触时间的反应技术以减少甲烷生成的技术构想。     

石脑油催化裂解生成甲烷的影响因素探析

对比分析了直馏石脑油热裂解和催化裂解过程中甲烷产率的差异及其根源,探索了工艺参数、催化剂活性和烃类分子结构对石脑油催化裂解反应中甲烷的产率和选择性的影响。结果表明:甲烷主要来自于石脑油的催化裂解反应,催化剂上的较强Brnsted酸中心是甲烷生成的活性中心;链烷烃催化裂解更易于生成甲烷;反应温度和油剂接触时间是影响甲烷生成的关键因素,对此提出采用适宜反应温度和大剂油比,在保证原料必要的转化深度的同时,开发超短接触时间的反应技术以减少甲烷生成的技术构想。     

2,5-二甲基己烷热裂化和催化裂化生成甲烷的机理研究

采用脉冲微反装置,在反应温度为550～650 ℃、低转化率（小于 15%）条件下,研究了2,5-二甲基己烷在石英砂和ZRP分子筛上的热裂化和催化裂化反应,分析了甲烷的生成机理。结果表明：2,5-二甲基己烷热裂化反应的主要产物是甲烷、丙烯和异丁烯,在链传递阶段,甲基自由基夺氢可由3条反应路径生成甲烷,叔C-H键对甲烷选择性的贡献大于90%;ZRP分子筛的择形催化作用影响2,5-二甲基己烷催化裂化的转化率和产物分布,甲烷由质子化裂化反应生成;分析热裂化反应与质子化裂化反应对甲烷生成的影响可知,甲烷主要由热裂化反应生成,且随反应温度升高,热裂化反应对甲烷生成的贡献逐渐增大。     

Effects of Impregnation Solvents on Catalytic Performance of Co-Ru-ZrO2/γ-Al2O3 Catalyst for Fischer-Tropsch Synthesis

Used ZrO₂ modified γ-Al₂O₃ as support, Co-Ru catalysts were prepared by incipient impregnation method. The effects of impregnation solvents on the performances of catalysts were examined. The catalyst was prepared with ethanol solution and high Co dispersion was obtained, exhibiting highest activity of CO hydrogenation, very low methane selectivity, and high heavy hydrocarbon C₅⁺ selectivity. The catalysts were prepared with aqueous solution and methanol solution, and the reaction behaviors were similar. The solvent isopropanol caused the lowest catalytic activity and highest methane selectivity. Increasing the reaction temperature enhanced the CO hydrogenation rate, and the CO conversion slightly increased the CO₂ selectivity and favored the formation methane and light hydrocarbons, while the chain growth probability decreased. For the catalyst prepared with ethanol, the CO conversion, the CH₄ selectivity, and the C₅⁺ selectivity were 94.16%, 5.65%, and 88.2%, respectively, and the chain growth probability was 0.87 at 493 K, 1.5 MPa, 800 h^-1, and n(H₂):n(CO) = 2.0 in feed.     

Effects of Impregnation Solvents on Catalytic Performance of Co-Ru-ZrO2/γ-Al2O3 Catalyst for Fischer-Tropsch Synthesis

Abstract

Used ZrO₂ modified γ-Al₂O₃ as support, Co-Ru catalysts were prepared by incipient impregnation method. The effects of impregnation solvents on the performances of catalysts were examined. The catalyst was prepared with ethanol solution and high Co dispersion was obtained, exhibiting highest activity of CO hydrogenation, very low methane selectivity, and high heavy hydrocarbon C₅ ⁺ selectivity. The catalysts were prepared with aqueous solution and methanol solution, and the reaction behaviors were similar. The solvent isopropanol caused the lowest catalytic activity and highest methane selectivity. Increasing the reaction temperature enhanced the CO hydrogenation rate, and the CO conversion slightly increased the CO₂ selectivity and favored the formation methane and light hydrocarbons, while the chain growth probability decreased. For the catalyst prepared with ethanol, the CO conversion, the CH₄ selectivity, and the C₅ ⁺ selectivity were 94.16%, 5.65%, and 88.2%, respectively, and the chain growth probability was 0.87 at 493 K, 1.5 MPa, 800 h^?1, and n(H₂):n(CO) = 2.0 in feed.     

THE CONVERSION OF SYNTHESIS GAS TO HIGHER OXYGENATED FUEL ON Rh-BASED CATALYSTS: EFFECT OF CHEMICAL ADDITIVES

In light of environmental concerns and the global economy, higher oxygenated fuel, such as ethanol, is a viable and attractive alternative to conventional gasoline. Presently, the major process to produce ethanol, the fermentation of corn, is economically inefficient. A more direct route, the reaction of synthesis gas (CO/H₂) to produce higher oxygenates (aldehydes and alcohols), appears to be a better method. Rhodium catalysts have been known to exhibit higher oxygenate activity and selectivity from synthesis gas. The mechanism involves CO dissociation followed by hydrogenation to form an adsorbed CH_X species. The CH_X intermediate can undergo either hydrogenation to form methane, chain propagation to form higher hydrocarbons, or CO insertion to form C₂ oxygenates. Experiments were performed to study the effects on the synthesis of higher alcohols from syngas of S, P, Cu, and Ag as additives to Rhodium supported on a silica support (Rh/Si0₂). The additive S was found to suppress the CO dissociation step, therefore lowering the overall product rate. The addition of P or Cu to the Rh catalyst enhance the CH_X intermediate hydrogenation, resulting in the increase of methane formation. The addition of Ag to Rh/SiO₂ promotes the CO insertion activity, therefore increasing the oxvtfenate selectivity.     

Cu-Fe混合氧化物催化剂上碱金属Na对CO_2加氢反应的影响

研究了由共沉淀法制备的Ｃｕ－Ｆｅ－Ｏ混合氧化物催化剂上残留的碱金属钠对ＣＯ２加氢的催化活性、选择性的影响，考察了反应温度对催化剂性能的影响。结果表明，在３００℃下，当残留的钠含量低于０．０４８％（ｍａｓｓ，下同）时，对ＣＯ２加氢反应产物的选择性影响不大；当钠含量在０．８２４％～８．１４％范围内时，有利于烯烃及乙醇的生成；当钠含量高于８．１４％时，促使１－丁烯向异丁烯转化。     

CO加氢合成乙醇用Rh基催化剂改进途径的探讨

针对Rh基催化剂在CO加氢反应过程中活性以及合成乙醇的选择性较低的问题,分析了反应机理和热力学,总结了催化剂研究进展,在此基础上讨论了改进Rh基催化剂活性和反应选择性的途径。     

CO_2加氢制低碳烯烃Fe/Silicalite-2催化剂研究 Ⅱ.催化剂制备研究

铁是ＣＯ２加氢制低碳烯烃的催化活性组分，其含量的增加将明显提高ＣＯ２转化率和反应产物中烃类摩分率；ＭｎＯ是Ｆｅ／Ｓｉ－２催化剂ＣＯ２加氢制低碳烯烃的有效助剂，提高ＭｎＯ含量，有利于提高ＣＯ２加氢制低碳烯烃的选择性，尤其可明显提高烃类产物中的烯、烷比值。结果还表明，ＭｎＯ助剂对甲烷生成量的影响不明显；而Ｋ２Ｏ助剂则可抑制甲烷生成，从而进一步提高低碳烯烃选择性，表明ＭｎＯ和Ｋ２Ｏ是Ｆｅ／Ｓｉ－２催化剂ＣＯ２加氢制低碳烯烃的重要助剂。     

浸渍溶剂对Rh-Mn-Li/SiO_2催化剂CO加氢性能的影响

采用CO加氢反应、CO-TPD、TPSR和XPS等技术,考察了水、甲醇、乙醇和异丙醇等浸渍溶剂对Rh-Mn-Li/S iO2催化剂CO加氢性能的影响。结果表明,以乙醇为浸渍溶剂的催化剂表现出最高的C2含氧化合物时空收率(YC2-oxy)和C2含氧化合物选择性(SC2-oxy),分别达686.1 g/(kg-cat.h)和73.8%;以甲醇和异丙醇为浸渍溶剂的催化剂上YC2-oxy也较高,但是SC2-oxy都比前者低;水溶液浸渍制备的催化剂有着较高的SC2-oxy,但是其YC2-oxy较低。以醇类为浸渍溶剂的催化剂的高活性与金属活性组分在催化剂表面富集而导致的更多活性中心的形成有关。催化剂表面非解离的CO比率增加有利于C2含氧化合物选择性的提高。     

预处理条件对Fe-Mn催化剂催化CO加氢合成低碳烯烃性能的影响

制备了一系列Fe-Mn催化剂,考察了预处理条件对其催化CO加氢合成低碳烯烃性能的影响。实验结果表明,用CO处理的催化剂较用H_2处理的催化剂具有较高的烯烃选择性;在CO气氛、300℃下还原4h的催化剂上,产物C_(2～4)烃中烯烃与烷烃的质量比可达5.88;碳化温度升高,重质烃含量增加;但在CO气氛、400℃下还原4h的催化剂上,产物中重质烃含量有所下降。XRD和XPS表征结果显示,用CO处理的催化剂中有碳化物生成,且高温、CO处理的催化剂表面有大量的碳化物生成;CO_2(CO)-TPD表征结果显示,碳化过程增强了催化剂的表面碱性,增强了CO的吸附能力,相对加氧能力减弱,烯烃选择性提高,促进了链增长。但同时CO吸附能力的增强,促进了CO高温预处理下的碳沉积,进而抑制了重质烃的生成。     

CO加氢Ni-Cu/ZnO双金属催化剂的研究

用程序升温还原（ＴＰＲ）、磁化率测量、ＸＰＳ等技术并结合ＣＯ加氢反应，对共沉淀方法制备的Ｎｉ－Ｃｕ／ＺｎＯ催化剂中组分间的相互作用进行了研究。结果表明，载体ＺｎＯ对ＣｕＯ具有分散作用，而与ＮｉＯ具有强相互作用；催化剂还原后Ｎｉ与Ｃｕ形成了Ｎｉ－Ｃｕ合金，而且Ｃｕ在合金表面有一定程度的富集；Ｎｉ与Ｃｕ间可能存在电子效应，即Ｃｕ向Ｎｉ供电子。在Ｎｉ－Ｃｕ／ＺｎＯ催化剂中，存在Ｎｉ－Ｃｕ金属间相互作用以及Ｎｉ－ＺｎＯ，Ｃｕ－ＺｎＯ金属－载体相互作用。金属间的相互作用能减弱（或破坏）金属与载体间的相互作用     

X-RAY DIFFRACTION CHARACTERIZATION OF Ag-Rh CATALYSTS FOR OXYGENATE AND HYDROCARBON SYNTHESIS

Ag-Rh/SiO₂ catalysts which exhibit activity and selectivity for oxygenate and hydrocarbon synthesis have been characterized by X-ray diffraction (XRD). XRD patterns show that the catalysts prepared using Rh chloride precursor contain Rh, Ag, AgCl, and AgClO₂ crystallites. The size of these crystallites varied with the amount of Ag in the catalyst. The variation in crystallite size of Rh, Ag, AgCl, and AgClO₂ with Ag/Rh ratio has an impact on the activity and selectivity for synthesis of oxygenates and hydrocarbons during CO hydrogenation and ethylene hydroformylation reactions. The selectivity towards oxygenates is decreased on the Ag-Rh catalysts due to the presence of AgCl and AgClO₂ crystallites on the catalyst surface. Ag-Rh catalyst with Ag/Rh ratio of 0.5 gives a higher activity and selectivity for ethanol and propanol during CO hydrogenation and ethylene hydroformylation than the other Ag-Rh catalysts. Ag-Rh catalysts prepared from Rh chloride and Ag nitrate precursors are less active and selective for oxygenate synthesis than those prepared from nitrate precursors. Ag-Rh catalysts for oxygenate synthesis should be prepared using nitrate precursors.