Study On Catalysts For Methyl Benzoate Hydrogenation

So far the dominating way of manufacture benzaldehyde is chlorinated hydrolysis,which is low yield,high pollution and not a green technology,the product often contains chlorine element,which limit the production to use in food,medicine additive and perfumery industry.It is difficult to meet people's daily needs,so develop a kind of environmentally friendly way to manufacture benzaldehyde is extremely urgent.Using methyl benzoate to produce no-chlorinated benzaldehyde can solve many technical defects effectively.The paper is aimed at the catalytic performance of metallic oxide catalyst using in methyl benzoate hydrogenation to produce benzaldehyde and benzyl alcohol.The experiment successfully developed K-Zn-Zr-Al and Mn-Cr-Zr catalysts.The main contents of this paper are as follows.1.Use fixed bed reactor to evaluate the catalytic performance in low pressure.The Zn-Zr-Al catalyst which prepared in equivalent-volume impregnation method has the better hydrogenation activity and selectivity in the produce of benzaldehyde.The optimum incorporation of zinc is 17.5 wt%.The conversion of methyl benzoate can be attained at 86.81%,and the selectivity of benzaldehyde can reach to 82.97%under the reaction condition of 430?,0.4 MPa,2.5 H2/MB molar ratio and 0.125 h-1 LHSV.2.Use impregnation method to modified and make the M-Zn-Zr-Al?Li,Na,K?catalyst.Experimental result shows the acid site and acid strength will reduce when catalyst was modified by alkali metal,which can significantly inhibit the produce of benzyl methyl ether and methylbenzene.2 wt%K-Zn-Al-Zr catalyst shows the optimum activity and selectivity in hydrogenation of methyl benzoate.3.The MnO/ZrO₂/Cr₂O₃ catalyst which produced by using chromium,manganese and zirconium dioxide show high catalyst performance.Under the optimum reaction condition and the incorporation of manganese is 8 wt%,the conversion of methyl benzoate can be attained at 84.6%,and the selectivity of benzaldehyde can reach to 97%.The connection between surface properties and catalyst performance of the catalysts were analyzed by means of XRD,TG and NH3-TPD.The paper also discussed the mechanism about hydrogenation reaction of methyl benzoate,which build a foundation for the industrialization of the hydrogenation of MB to produce benzaldehyde and benzyl alcohol.