Catalyst for producing maleic anhydrid(e) by benzene gas-phase oxidation with high load and high yield

Abstract

The invention relates to a catalyst for manufacturing maleic anhydride through the high-load and high-yield benzene gas-phase oxidation. A fixed-bed tubular reactor sequentially comprises an A section and a B section which are composed of catalysts with different performances along the inlet direction of reaction mixture gas; the A section is 40 to 60 percent of the total bed height, and the B section is 60 to 40 percent of the total bed height. The catalyst in the A section has the active phase composition that the ratio of V2O5:MoO3:P2O5:Na2O:NiO:Re2O3 equals to 1:(0.4 to 0.9):(0.01 to 0.08):(0.05 to 0.100):(0.005 to 0.500):(0.0001 to 0.0010), wherein, Re is any two of following rare earth elements that are Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu. The catalyst in the B section has the active phase composition that the proportion of the Re2O3 is 2 to 3 times of that of the Re2O3 in the A section, the proportion of the P2O5 is (0.005 to 0.040)mol, and the proportions of other oxides are the same with that in the A section. The catalyst can lead maleic anhydride production equipment to increase about 25 percent production capacity without increasing any investment, and the benzene consumption and the energy consumption can be obviously reduced.

Description

technical field [0001] The invention relates to the technical field of catalysts, in particular to a catalyst for preparing maleic anhydride by gas-phase oxidation of benzene with high load and high yield. Background technique [0002] The gas-phase fixed-bed catalytic oxidation of benzene to produce maleic anhydride has a history of decades at home and abroad. The catalysts used are all vanadium molybdenum oxymaleic anhydride catalysts, but due to the differences in active material formulations, carriers, preparation processes and usage methods, a large number of patents have been published, and a variety of vanadium molybdenum oxymaleic anhydrides have also appeared on the foreign market. catalyst. All these maleic anhydride vanadium molybdenum oxygen catalysts can be collectively referred to as ordinary maleic anhydride catalysts. The benzene load of a single tube is generally 100-110g / h, and individual factories, such as Tianjin Zhonghe Chemical Plant, can only reach 12...

AI Technical Summary

Problems solved by technology

④Use a stainless steel tube with an inner diameter of 25mm and a length of 3500mm to do the evaluation test. When the total bed height is 2500mm and the salt temperature is 355-365°C, the yield of maleic anhydride is 97-98% (based on 100% benzene), but the bed layer is not given Hot spots and benzene conversion

First, it is right that section A should control the activity, but it adopts a lower P than section B 2 o 5 It will only increase the activity of the catalyst without controlling the activity

It is right to increase the activity of the B segment, but it greatly increases the P 2 o 5 The amount (0.35mol), which can only greatly reduce the activity, in fact, this formula will only increase the activity of the A segment and reduce the activity of the B segment

Second, the immediate biggest difficulty with high loads is that the bed hot spot is too high, and this author does not mention the hot spot data

Thirdly, the author chooses a reaction tube with an inner diameter of 25mm to do the evaluation test. However, the tubes with an inner diameter of 21mm are used in the fixed bed tubes of the benzene method at home and abroad. The tube with an inner diameter of 25mm must have a very high hot spot for the strongly exothermic benzene oxidation reaction. Can't reach high benzene load at all

Their C segment hopes to increase the activity, but uses more P than the B segment 2 o 5 (0.02), the result of this must be that the B segment has high activity and low selectivity, and the C segment has low activity and relatively high selectivity

In short, their patented invention cannot achieve the results they stated

[0007] The high-load maleic anhydride catalyst sold in Italy in China, although the load reaches 150-170g / h·tub, the yield of maleic anhydride is 2-4% lower than that of ordinary maleic anhydride catalysts, and the acid water produced has a heavy color, causing post-treatment Blocked tower, benzene consumption is 1210-1220kg / t, 40-50kg / t higher than ordinary type