Study On Vapor-phase Aldehyde Hydrogenation Catalyst Preparation By High Gravity Precipitation Method

Butyl alcohol and octanol are produced by hydrogenation reaction, they are important organic chemical feedstocks and chemical additives. Butyl alcohol and octanol can be used in producing plasticizer, plastics and rubber products.Aldehyde hydrogenation reaction is an important method to produce butylalcohol and octanol, which can determine quality and yield of butyl alcohol and octanol product. Aldehyde hydrogenation reaction can be divided into liquid-phase method and vapor-phase method according to catalyst and feed phase. Ni catalyst is used in liquid-phase, reactor is packed bed; Cu-based catalyst is used in vapor-phase method, reactor is industrial multitubular fixed-bed. Vapor-phase method is widely used because of lower reaction pressure, simpler process equipment, Most butyl alcohol and octanol units use vapor-phase method in China. Nowdays, vapor-phase aldehyde hydrogenation catalyst is Cu-Zn type catalyst.The relationship of Cu-Zn catalyst activity and Cu dispersion is linear, the dispersion increment of active component Cu is beneficial to hydrogenation activity and selectivity of aldehyde hydrogenation catalyst. Cu-Zn catalyst is made by precipitation method in the stirred autoclave. But the structure of conventional stirred autoclave resulted in bad microscopic mixing. The precipitation reaction and the ageing reaction proceed in the same stirred autoclave, the oversaturation degree is different in the process of the crystal growth, producing different particle sizes and large particles, and the active component is not well-distributed.The Cu-Zn catalyst for vapor-phase aldehyde hydrogenation was prepared by high gravity precipitation method in this paper. The precipitation reaction was carried out in the high gravity environment, it can achieve uniform mixing in the microcosmic condition. The products of precipitation reaction were transformed away from the precipitation system immediately, the ageing reaction was completely carried out in the macroscopic mixing region, so the crystal sizes of prepared catalyst were smaller and well-distributed, effectually improving the dispersion of active component.The affecting factors of catalyst prepared by high gravity precipitation method were analyizing, the preparing process was optimized, and the catalysts were characterized by some techniques. The evaluation test of vapor-phase aldehyde hydrogenation catalyst was carried out in a 300ml hydrogenation test unit. Using Daqing Petrochemical Company butyl aldehyde and octenal as feedstocks. The operating conditions are as follows: pressure of 0.45MPa, temperature of 180～200℃, LHSV of 0.4h^-1, H₂ to aldehyde volume ratio of 800:1. The conversion of butyl aldehyde/octenal is more than 99.5%, selectivity of butyl alcohol/ octanol is more than 99.0%, the catalyst exhibits better hydrogenation activity and selectivity.