通过调控铝源合成了四种HZSM-5分子筛,并将其应用于催化甲缩醛(DMM)气相羰基化合成甲氧基乙酸甲脂(MMAc)反应。结果表明,改变合成凝胶体系中的铝源种类,可以制备出织构性质、酸性特征相近,但骨架铝分布不同、催化羰基化性能迥异的HZSM-...通过调控铝源合成了四种HZSM-5分子筛,并将其应用于催化甲缩醛(DMM)气相羰基化合成甲氧基乙酸甲脂(MMAc)反应。结果表明,改变合成凝胶体系中的铝源种类,可以制备出织构性质、酸性特征相近,但骨架铝分布不同、催化羰基化性能迥异的HZSM-5分子筛。其中,使用硝酸铝与硫酸铝作为铝源制备的分子筛HZ-N与HZ-S表现出更为优异的催化活性,HZ-N对应的DMM转化率与MMAc选择性分别为25.3%与58.9%,HZ-S对应的DMM转化率与MMAc选择性分别为28.7%与64.6%。采用Co-ZSM-5的UV-vis-DRS与27 Al MAS NMR等表征手段详细分析证实,硝酸铝与硫酸铝作为铝源时,更多的骨架铝优先落位于HZSM-5分子筛交叉孔道,其在催化DMM羰基化反应过程中起主导作用,落位比例高,更有利于反应的进行,反之可能导致较低的DMM转化率以及更高的副产物选择性。展开更多
A novel Mo/C catalyst, which are reduced in H2 after sulfidizaing ammonium heptamolybdate with （NH4）2S aqueous solution, has a high activity and selectivity for ethanol vapor phase carbonylation to ethyl propionate ...A novel Mo/C catalyst, which are reduced in H2 after sulfidizaing ammonium heptamolybdate with （NH4）2S aqueous solution, has a high activity and selectivity for ethanol vapor phase carbonylation to ethyl propionate without addition of any promoter in the feed. Ethanol carbonylation is carried out in a fixed bed reactor with a continuous flow system at atmospheric pressure. This catalyst has a higher initial activity and selectivity; the catalytic activity reaches steady state after carbonylation reaction for 30 min. Higher temperatures led to a sharp decrease of the carbonylation activity and to an increase of the selectivities of ethene and ether. The optimal reaction conditions are as follows: reaction temperature is 553 K; n（C2H5OH）/n（CO）=4/1; GHSV=4.0 L/（g cat·h）. Under these conditions, the conversion of ethanol is 80%, the selectivity of ethyl propionate is 80.6% and the space-time yield is 1.157×10 -2 mol/（g cat·h）. This result is surprisingly better than that of ethanol vapor phase carbonylation over Ni-Zn/C catalyst with addition of ethyl iodide promoter to the feed [n（C2H5OH）/n（C2H5I）=10/1], especially, this novel Mo/C catalyst has a significantly higher selectivity. No carbonylation product is found over Ni base catalyst without addition of the promoter. This research demonstrates that novel Mo/C catalyst may be promising for ethyl propionate production from the carbonylation of ethanol at atmospheric pressure, without requiring ethyl iodide as promoter. This novel catalyst is found to be a non-crystalline by X-ray diffraction. The Mo content in the catalyst is 10%.展开更多
A novel heterogeneous sulfided Mo/C catalyst was used for the direct vapor phase carbonylation of methanol Experiments were designed with the elimination of mass transfer resistances to obtain data The data of primary...A novel heterogeneous sulfided Mo/C catalyst was used for the direct vapor phase carbonylation of methanol Experiments were designed with the elimination of mass transfer resistances to obtain data The data of primary reactions in the carbonylation were collected via a differential tubular reactor Feed composition was varied to examine the effect of partial pressures of reactants on the reaction rate Power law rate models were employed to express the conversion of methanol and the formations of methyl acetate and methane Adequate results were obtained with the models to represent the experimental data The reaction orders of methyl acetate formation with respect to methanol and CO were found to be 1 2 and 0 35 respectively on the novel Mo/C catalyst, and the reaction activation energy was 106?kJ/mol At the same time, the reaction mechanism of direct vapor phase carbonylation of methanol was presented The initial step of this reaction was suggested to be the cleavage of methanol to form CH + 3 M, followed by adsorbed CO insertion into the metal methyl bond to form CH 3C(O) + M, which further interacts with methanol to form methyl展开更多
In this article, Ni/CNTs(carbon nano-tubes) catalyst′s effect for methanol vapor-phase carbonylation under atmospheric pressure were studied. The relations between the catalyst activity and drying condition, the temp...In this article, Ni/CNTs(carbon nano-tubes) catalyst′s effect for methanol vapor-phase carbonylation under atmospheric pressure were studied. The relations between the catalyst activity and drying condition, the temperature of thermal treatment(with N2) and reduction(with H2) were investigated. The catalyst showed high activity when catalyst were dried step by step. The optimal temperature for thermal treatment with N2 and reduction with H2 were 300 ℃ and 700 ℃respectively.展开更多
文摘通过调控铝源合成了四种HZSM-5分子筛,并将其应用于催化甲缩醛(DMM)气相羰基化合成甲氧基乙酸甲脂(MMAc)反应。结果表明,改变合成凝胶体系中的铝源种类,可以制备出织构性质、酸性特征相近,但骨架铝分布不同、催化羰基化性能迥异的HZSM-5分子筛。其中,使用硝酸铝与硫酸铝作为铝源制备的分子筛HZ-N与HZ-S表现出更为优异的催化活性,HZ-N对应的DMM转化率与MMAc选择性分别为25.3%与58.9%,HZ-S对应的DMM转化率与MMAc选择性分别为28.7%与64.6%。采用Co-ZSM-5的UV-vis-DRS与27 Al MAS NMR等表征手段详细分析证实,硝酸铝与硫酸铝作为铝源时,更多的骨架铝优先落位于HZSM-5分子筛交叉孔道,其在催化DMM羰基化反应过程中起主导作用,落位比例高,更有利于反应的进行,反之可能导致较低的DMM转化率以及更高的副产物选择性。
文摘A novel Mo/C catalyst, which are reduced in H2 after sulfidizaing ammonium heptamolybdate with （NH4）2S aqueous solution, has a high activity and selectivity for ethanol vapor phase carbonylation to ethyl propionate without addition of any promoter in the feed. Ethanol carbonylation is carried out in a fixed bed reactor with a continuous flow system at atmospheric pressure. This catalyst has a higher initial activity and selectivity; the catalytic activity reaches steady state after carbonylation reaction for 30 min. Higher temperatures led to a sharp decrease of the carbonylation activity and to an increase of the selectivities of ethene and ether. The optimal reaction conditions are as follows: reaction temperature is 553 K; n（C2H5OH）/n（CO）=4/1; GHSV=4.0 L/（g cat·h）. Under these conditions, the conversion of ethanol is 80%, the selectivity of ethyl propionate is 80.6% and the space-time yield is 1.157×10 -2 mol/（g cat·h）. This result is surprisingly better than that of ethanol vapor phase carbonylation over Ni-Zn/C catalyst with addition of ethyl iodide promoter to the feed [n（C2H5OH）/n（C2H5I）=10/1], especially, this novel Mo/C catalyst has a significantly higher selectivity. No carbonylation product is found over Ni base catalyst without addition of the promoter. This research demonstrates that novel Mo/C catalyst may be promising for ethyl propionate production from the carbonylation of ethanol at atmospheric pressure, without requiring ethyl iodide as promoter. This novel catalyst is found to be a non-crystalline by X-ray diffraction. The Mo content in the catalyst is 10%.
文摘A novel heterogeneous sulfided Mo/C catalyst was used for the direct vapor phase carbonylation of methanol Experiments were designed with the elimination of mass transfer resistances to obtain data The data of primary reactions in the carbonylation were collected via a differential tubular reactor Feed composition was varied to examine the effect of partial pressures of reactants on the reaction rate Power law rate models were employed to express the conversion of methanol and the formations of methyl acetate and methane Adequate results were obtained with the models to represent the experimental data The reaction orders of methyl acetate formation with respect to methanol and CO were found to be 1 2 and 0 35 respectively on the novel Mo/C catalyst, and the reaction activation energy was 106?kJ/mol At the same time, the reaction mechanism of direct vapor phase carbonylation of methanol was presented The initial step of this reaction was suggested to be the cleavage of methanol to form CH + 3 M, followed by adsorbed CO insertion into the metal methyl bond to form CH 3C(O) + M, which further interacts with methanol to form methyl
文摘In this article, Ni/CNTs(carbon nano-tubes) catalyst′s effect for methanol vapor-phase carbonylation under atmospheric pressure were studied. The relations between the catalyst activity and drying condition, the temperature of thermal treatment(with N2) and reduction(with H2) were investigated. The catalyst showed high activity when catalyst were dried step by step. The optimal temperature for thermal treatment with N2 and reduction with H2 were 300 ℃ and 700 ℃respectively.
