Ni-Zn／C催化剂上乙醇气相羰基化

GAS PHASE CARBONYLATION OF ETHANOL ON Ni Zn/C CATALYST

对镍催化剂上常压下乙醇气相羰基化合成丙酸及丙酸乙酯进行了研究．结果发现，Ｎｉ－Ｚｎ／Ｃ催化剂比Ｎｉ／Ｃ具有更高的活性与选择性．实验对催化剂中Ｎｉ及Ｚｎ含量进行了优化，Ｎｉ含量５％，Ｚｎ含量３．５％时最佳．考察了反应温度对产物分布的影响，结果表明２５０℃为最佳反应温度．采用程序升温脱附技术（ＴＰＤ）对促进剂碘乙烷在活性炭，Ｎｉ／Ｃ，Ｚｎ／Ｃ及Ｎｉ－Ｚｎ／Ｃ上的行为进行了考察．实验结果表明，乙醇的甲烷化产物是通过碘乙烷裂解而成．提出了乙醇羰基化与甲烷化反应连在一起的催化循环网络．

Gas phase carbonylation of ethanol on Ni/C and Ni Zn/C catalysts was investigated under atmospheric pressure. Ni Zn/C was found to have a significantly higher activity and selectivity than Ni/C. The effects of Zn and Ni content on ethanol conversion and product distribution were examined, and the optimum content of Ni and Zn were 5% and 3 5% respectively. It was found that the selectivity for propionic acid increased and the selectivity for ethyl propionate decreased with the reaction temperature. The yield of carbonylation products existed a maximum at 250℃. The behaviour of C 2H 5I on activated carbon, Ni/C, Zn/C and Ni Zn/C was studied by TPD. It was showed that (1) TPD profile of C 2H 5I from activated carbon had a single peak, and the desorption activation energy was 55 6 kJ/mol; (2) the TPD profiles of C 2H 5I from Ni/C, Zn/C and Ni Zn/C catalysts had two peaks, the first one at lower temperature was C 2H 5I, the second one at higher temperature was CH 4, produced by C 2H 5I methanation. The addition of Zn to Ni/C decreased C 2H 5I methanation. The kinetic equations of methanation for different catalysts were studied. The overall reaction path of ethanol carbonylation and the mechanism of CH 4 formation were described.