Method for producing a multi metal oxide catalyst, method for producing unsaturated aldehydes and/or carboxylic acids and band calcination device

Abstract

A catalyst suitable for the gas-phase oxidation of organic compounds to α,β-unsaturated aldehydes and/or carboxylic acids and having an active phase comprising a multimetal oxide material is prepared by a process in which a particulate catalyst precursor which contains oxides and/or compounds of the elements other than oxygen which constitute the multimetal oxide material, which compounds can be converted into oxides, is prepared and said catalyst precursor is converted by calcination into a catalytically active form, wherein a stream of the particulate catalyst precursor is passed at substantially constant speed through at least one calcination zone at constant temperature for calcination.

1 . A process for the preparation of a catalyst suitable for the gas phase oxidation of organic compounds to α,β-unsaturated aldehydes and/or carboxylic acids and having an active phase of a multimetal oxide material, in which a particulate catalyst precursor which contains oxides and/or compounds of the elements other than oxygen which constitute the multimetal oxide material, which compounds can be converted into oxides, is prepared and said catalyst precursor is converted by calcination into a catalytically active form, wherein a stream of the particulate catalyst precursor is passed at substantially constant speed through at least one calcination zone for calcination, the maximum variation of the temperature as a function of time and the maximum local temperature difference in the calcination zone each being <5° c. 
   
   
       2 . A process as claimed in  claim 1 , wherein the multimetal oxide material contains at least one first metal selected from molybdenum and tungsten and at least one second metal selected from bismuth, tellurium, antimony, tin, copper, iron, cobalt and/or nickel. 
   
   
       3 . A process as claimed in  claim 2 , wherein the multimetal oxide material has the formula I or II,
   [X 1   a X 2   b O x]   p [X 3   c X 4   d X 5   e X 6   f X 7   g X 2   h O y ] q   (I)     Mo 12 Bi i X 8   k Fe l X 9   m X 10   n O z   (II)   
     where
 X 1  is bismuth, tellurium, antimony, tin and/or copper, 
 X 2  is molybdenum and/or tungsten, 
 X 3  is an alkali metal, thallium and/or samarium, 
 X 4  is an alkaline earth metal, nickel, cobalt, copper, manganese, zinc, tin, cadmium and/or mercury, 
 X 5  is iron, chromium, cerium and/or vanadium, 
 X 6  is phosphorus, arsenic, boron and/or antimony, 
 X 7  is a rare earth metal, titanium, zirconium, niobium, tantalum, rhenium, ruthenium, rhodium, silver, gold, aluminum, gallium, indium, silicon, germanium, lead, thorium and/or uranium, 
 a is from 0.01 to 8, 
 b is from 0.1 to 30, 
 c is from 0 to 4, 
 d is from 0 to 20, 
 e is from 0 to 20, 
 f is from 0 to 6, 
 g is from 0 to 15, 
 h is from 8 to 16, 
 x and y are numbers which are determined by the valency and frequency of the elements other than oxygen in I, 
 p and q are numbers whose ratio p/q is from 0.1 to 10, 
 X 8  is cobalt and/or nickel, 
 X 9  is silicon and/or aluminum, 
 X 10  is an alkali metal, 
 i is from 0.1 to 2, 
 k is from 2 to 10, 
 l. is from 0.5 to 10, 
 m is from 0 to 10, 
 n is from 0 to 0.5, 
 z is a number which is determined by the valency and frequency of the elements other than oxygen in II. 
 
   
   
       4 . A process as claimed in any of the preceding claims, in which a gas stream is passed through the catalyst precursor stream perpendicularly to the direction of advance of the catalyst precursor in the calcination zone. 
   
   
       5 . A process as claimed in any of the preceding claims, in which the catalyst precursor is passed through at least two calcination zones which are thermostated at different temperatures. 
   
   
       6 . A process as claimed in any of the preceding claims, in which the maximum variation of the temperature in the calcination zone as a function of time is ≦3° C. 
   
   
       7 . A process as claimed in  claim 6 , in which the maximum variation of the temperature in the calcination zone as a function of time is ≦2° C. 
   
   
       8 . A process as claimed in any of the preceding claims, in which the maximum local temperature difference in the calcination zone is ≦3° C. 
   
   
       9 . A process as claimed in  claim 9 , in which the maximum local temperature difference in the calcination zone is ≦2° C. 
   
   
       10 . A batch of a catalyst, which has a multimetal oxide material of the formula I or II stated in  claim 3  as the active phase, of least 100 kg, the standard deviation of the activity of any random samples taken from the batch, expressed as the temperature at which a propene conversion of 95% is obtained if a mixture of 5% by volume of propene, 9.5% by volume of oxygen and 85.5% by volume of nitrogen passed over 100 g of catalyst at 100 l (S.T.P.)/h, being less than 7° C. 
   
   
       11 . A process for the preparation of α,β-monoethylenically unsaturated aldehydes and/or carboxylic acids, in which a gaseous stream of an alkane, alkanol, alkene and/or alkenal of 3 to 6 carbon atoms is passed, at elevated temperatures in the presence of molecular oxygen, through at least one reaction zone which contains at least one batch of a catalyst as claimed in  claim 10 . 
   
   
       12 . A process as claimed in  claim 11 , in which the loading of the catalyst with the alkane, alkanol, alkene and/or alkenal is at least 160 l (S.T.P.) per l of catalyst per hour. 
   
   
       13 . A process as claimed in  claim 11  or  12 , in which the alkene is propene, and acrolein is obtained. 
   
   
       14 . A process as claimed in any of  claims 11  to  13 , in which the gaseous stream is passed in succession through a first and a second reaction zone, the temperature of the first reaction zone being from 300 to 330° C. and the temperature of the second reaction zone being from 300 to 365° C. and being at least 5° C. above the temperature of the first reaction zone, and the first reaction zone extending to a conversion of the alkane, alkanol, alkene and/or alkenal of from 40 to 80 mol %. 
   
   
       15 . A belt calcination apparatus comprising at least one heatable chamber and a gas-permeable conveyor belt passing through the chamber and intended for holding the particulate material, wherein means for producing a gas circulation based on forced convection are provided in the chamber. 
   
   
       16 . A belt calcination apparatus as claimed in  claim 15 , wherein the means comprise a fan. 
   
   
       17 . A belt calcination apparatus as claimed in  claim 15  or  16 , wherein the means comprise gas-guiding apparatuses for guiding the gas circulation inside the chamber, and the gas-guiding apparatuses inside the chamber each extend along the edge of the conveyor belt, substantially in a plane perpendicular to the support area of the conveyor belt. 
   
   
       18 . A belt calcination apparatus as claimed in any of  claims 15  to  17 , wherein at least two heatable chambers which can be regulated to different temperatures are provided. 
   
   
       19 . A belt calcination apparatus as claimed in any of  claims 15  to  18 , wherein the volume of the gas circulating in the chamber per unit time is greater than the volume of the gas fed into or removed from the chamber per unit time.