EFFECT OF SURFACTANT ON STRUCTURE AND PERFORMANCE OF CATALYSTS FOR DME SYNTHESIS IN SLURRY BED

摘要

IntroductionIn recent years, much attention has been paid to slurry reactor due to its advantages, such as simple construction, isothermal condition, and on-line catalysts addition and withdrawal [1]. However, a major problem to restrict the commercial application of slurry DME synthesis technology is due to short lifetime and bad stability of catalyst for CO hydrogenation. Many researchers [2] reported that the composite catalyst, which is active for vapor phase DME synthesis deactivates at a very high rate when used for slurry phase DME synthesis. But the reason of deactivation is not clear and a few reports on solving the problem are available. Currently, in slurry phase DME synthesis process, the solid catalyst is suspended in the inert organic medium, which leads easily to catalyst subsiding, poor fluidity and activity dropping [3]. This is probable because the conditions in which the solid catalyst is prepared dose not match that the catalyst is used. To resolve the problem, we recently proposed a new slurry catalyst preparation technology -Complete Liquid Phase Preparation Technology -for slurry reactor [4]. The method prepares slurry catalyst directly from solution to the slurry, avoids the conventional drying and calcination procedure. The novel method was first used to prepare Cu-Zn-AI catalyst for the direct synthesis of DME from synthesis gas in a slurry reactor, and the results indicated that the stability of slurry catalyst was good during the reaction of 440h, no significant deactivation has been found.