Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia load...Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The Mg O–SBA-15 supports and Pd–Pb/Mg O–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of Mg O improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3 Pb particles on magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts was smaller than that on the pure silica-based Pd–Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts had higher activity than pure silica-based Pd–Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd–Pb/SBA-15 catalysts and Pd–Pb/Mg O–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by Mg O, which led to the different Pd3 Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity.展开更多
A series of supported intermetallic Pb-Pb catalysts were prepared with the impregnation method by changing the support(silica,molecular sieve or γ-alumina)and the pore size.The chemical states of the two metals were ...A series of supported intermetallic Pb-Pb catalysts were prepared with the impregnation method by changing the support(silica,molecular sieve or γ-alumina)and the pore size.The chemical states of the two metals were characterized by XPS analysis,the process for producing methyl methacrylate based on the direct oxidative esterification of methacrolein with methanol in the presence of oxygen was performed in a slurry reactor with the above-mentioned catalysts.The influence of the calcination temperature and the kinds of support as well as the pore size on catalytic activity had been extensively investigated.Under the conditions of temperature at 80℃,catalyst 3.8%(ω)and the reaction time 2 h,the conversion rate of methacrolein reached 85%,the selectivity and the yield of methyl methacrylate were 90% and 76.5%,respectively.展开更多
固定甲苯、催化剂及配体用量,对乙烯在甲苯溶剂中的氢甲酰化反应动力学进行了研究。以反应计量比为1:1:1的乙烯、一氧化碳和氢气为反应混合气,测定了100℃、93℃和81℃下反应压力随时间的变化曲线,通过动力学方程求解获得了3种气体总的...固定甲苯、催化剂及配体用量,对乙烯在甲苯溶剂中的氢甲酰化反应动力学进行了研究。以反应计量比为1:1:1的乙烯、一氧化碳和氢气为反应混合气,测定了100℃、93℃和81℃下反应压力随时间的变化曲线,通过动力学方程求解获得了3种气体总的反应级数、反应速率常数和活化能,得到反应的活化能为55.0 k J/mol。进一步通过一氧化碳和氢气过量,得到了乙烯的反应级数。然后通过氢气过量,得到了乙烯和一氧化碳的总反应级数,随后即计算得到了一氧化碳和氢气各自的反应级数,表明一氧化碳分压高会抑制反应速率,而增加乙烯和氢气分压对反应速率有促进作用。展开更多
基金Supported by the Key Program of the National Natural Science Foundation of China(21036007)the National High-Tech Project of China(2012AA062903)
文摘Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The Mg O–SBA-15 supports and Pd–Pb/Mg O–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of Mg O improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3 Pb particles on magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts was smaller than that on the pure silica-based Pd–Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd–Pb/Mg O–SBA-15 catalysts had higher activity than pure silica-based Pd–Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd–Pb/SBA-15 catalysts and Pd–Pb/Mg O–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by Mg O, which led to the different Pd3 Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity.
基金Supported by the National Natural Science Foundation of China(No.20436050)and the National High Technology Development Program of China(No.2004AA649240).
文摘A series of supported intermetallic Pb-Pb catalysts were prepared with the impregnation method by changing the support(silica,molecular sieve or γ-alumina)and the pore size.The chemical states of the two metals were characterized by XPS analysis,the process for producing methyl methacrylate based on the direct oxidative esterification of methacrolein with methanol in the presence of oxygen was performed in a slurry reactor with the above-mentioned catalysts.The influence of the calcination temperature and the kinds of support as well as the pore size on catalytic activity had been extensively investigated.Under the conditions of temperature at 80℃,catalyst 3.8%(ω)and the reaction time 2 h,the conversion rate of methacrolein reached 85%,the selectivity and the yield of methyl methacrylate were 90% and 76.5%,respectively.
文摘固定甲苯、催化剂及配体用量,对乙烯在甲苯溶剂中的氢甲酰化反应动力学进行了研究。以反应计量比为1:1:1的乙烯、一氧化碳和氢气为反应混合气,测定了100℃、93℃和81℃下反应压力随时间的变化曲线,通过动力学方程求解获得了3种气体总的反应级数、反应速率常数和活化能,得到反应的活化能为55.0 k J/mol。进一步通过一氧化碳和氢气过量,得到了乙烯的反应级数。然后通过氢气过量,得到了乙烯和一氧化碳的总反应级数,随后即计算得到了一氧化碳和氢气各自的反应级数,表明一氧化碳分压高会抑制反应速率,而增加乙烯和氢气分压对反应速率有促进作用。
