水对Ni/MgAlO催化丙酮加氢的影响

研究了H2O对Ni/MgAlO催化剂上丙酮加氢为异丙醇的催化反应的影响。结果发现，在丙酮中添加少量H2O可提高丙酮转化率，但超过5%的H2O量则会显著降低催化剂活性。吸附量热结果表明，催化剂表面吸附少量H2O会明显降低异丙醇的吸附热，但对丙酮吸附热的影响较小，这也许是反应体系中少量的H2O能促进丙酮加氢活性的原因之一。当催化剂表面吸附较多H2O后，丙酮、异丙醇和H2的吸附热都降低了，因此反而抑制了丙酮的加氢反应。此外，红外光谱结果表明，预吸附水抑制了催化剂表面异丙醇脱氢生成丙酮，并抑制吸附的丙酮在表面生成烯醇盐或异丙叉丙酮等物种，这也许是少量水能促进丙酮加氢生成异丙醇的另一个重要原因。

Effects of water on the hydrogenation of acetone over Ni/MgAlO catalysts

The effect of water on the hydrogenation of acetone to isopropanol (IPA) on the Ni/MgAlO catalyst was studied. It was found that small amount of water added in the acetone promoted the conversion of acetone to IPA, while more H2O added (>5%) significantly decreased the conversion of acetone. Microcalorimetric adsorption results showed that the presence of small amount of pre‐adsorbed water (4%coverage) enhanced the adsorption of acetone while inhibited the adsorption of IPA on Ni, which might be the important reasons for the promotion effect of some water on the hydrogena‐tion of acetone to IPA. On the other hand, the heats for the adsorption of H2, acetone and IPA on the Ni/MgAlO were significantly decreased when more water was pre‐adsorbed, which might explain the inhibition effect of more water on the hydrogenation of acetone. The results of infrared spec‐troscopy revealed that the presence of water suppressed the dehydrogenation of adsorbed IPA to acetone and the formation of enolate and mesityl oxide species from adsorbed acetone, which might be the other reasons for the positive effect of water on the hydrogenation of acetone to IPA.