Catalyst process of making

Details Catalyst process of making Catalyst process of making

2002-12-17

2004-07-13

Silverman, Samuel S. (Department: 1754)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Metal, metal oxide or metal hydroxide

C502S305000, C502S311000, C502S439000

Reexamination Certificate

active

06762148

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a novel catalyst, and more particularly to a catalyst suitable for use in the production of acrylic acid by vapor-phase catalytic oxidation of acrolein with molecular oxygen.
BACKGROUND ART
As a catalyst for the production of an unsaturated acid by vapor-phase catalytic oxidation of the unsaturated aldehyde, there are known, for examples, the catalyst obtained by tableting a catalytically active component composition, the catalyst obtained by molding a catalytically active component with auxiliary components into a globule or a ring, and the catalyst obtained by supporting a catalytically active component on inactive carriers with binders (hereinafter called coated catalyst).
For the preparation of the coated catalyst, Japanese Patent Laid-Open No.11709/1976 disclosed the method of coating by rolling the active component and the carriers in a rotating drum or jar; Japanese Patent Laid-Open No.153889/1977 disclosed the method of coating either by spraying the aqueous suspension of a preliminarily calcined active component over the carriers or by spreading the active component over vigorously moving carriers; and Japanese Patent Laid-Open No.85139/1989 disclosed the method of production using various granulators.
In the industrial plant for producing acrylic acid by vapor-phase catalytic oxidation of acrolein with molecular oxygen, the catalyst is packed into an as long as 5 m reaction tube from the upper side. Therefore, if the coated catalyst having a weak mechanical strength packed, the catalytically active components composition is peeled out and pulverized into powder and it cause a problem that they raise abnormally the pressure inside the tube during the reaction. So, the catalyst is demanded to have a large mechanical strength in property (such as little attrition resistance).
In recent years, the production of acrylic acid by vapor-phase catalytic oxidation of acrolein trends towards “high load reaction condition”, that is, to increase the amount of acrolein supplied per unit volume of the catalyst. Since the oxidation reaction of acrolein is exothermic, such increased amount of acrolein brings about hot spots, which are likely to drive out the catalytic components including molybdenum, a constitutional element of the catalyst. As the defect, difference in pressure inside the reaction tube increases with the elapse of reaction time, decreasing the reaction merits (such as conversion of acrolein and acrylic acid yield) and blocking a long operation.
Such a situation demands to develop the highly active catalyst that would enable the operation at low reaction temperature. The present applicant made a diligent study to solve these problems, disclosing in Japanese Patent Laid-Open No.299797/1996 filed previous to the present application that the catalyst having a certain X-ray diffraction pattern was highly active and had a large mechanical strength. It also disclosed that it was preferable to use antimony trioxide subjected to no chemical treatment for an antimony-containing compound.
DISCLOSURE OF THE INVENTION
The present applicant has made another diligent study to solve these problems, finding to complete the present invention that the catalyst obtained by using a certain material is highly active for the oxidation reaction of acrolein and has a large mechanical strength. Namely, the present inventors have studied to reveals that antimony acetate used for the source material can provide the catalyst having larger mechanical strength, high activity and good reproducibility. The present invention relates to an antimony-containing molybdenum catalyst produced by using antimony acetate for an antimony source material, and more particularly to the followings:
(1) A catalyst in which the catalytically active component constitution is represented by the formula (1):
 Mo
12
V
a
W
b
Cu
c
Sb
d
X
e
Y
f
Z
g
O
h
  (1)
(in the formula, Mo, V, W, Cu, Sb and O represent molybdenum, vanadium, tungsten, copper, antimony and oxygen respectively; X represents at least one element selected from the group consisting of alkali metals and thalium; Y represents at least one element selected from the group consisting of magnesium, calcium, strontium, barium and zinc; Z represents at least one element selected from the group consisting of niobium, cerium, tin, chromium, manganese, iron, cobalt, samarium, germanium, titanium and arsenic; a, b, c, d, e, f, g and h represent atomic ratios of their respective elements, with 0<a≦10, 0≦b≦10, 0<c≦6, 0<d≦10, 0≦e≦0.5, 0≦f≦1, 0≦g<6, based on 12 of molybdenum element; h is the number of oxygen atoms required to satisfy the total valence of the other elements), said catalytically active component composition comprising being produced by using antimony acetate for an antimony source material.
(2) A coated catalyst, wherein said catalyst is a coated catalyst obtained by coating said catalytically active component composition according to the above (1) on an inactive carrier, the coated catalyst obtained through the process including the following steps (a) to (c):
(a) Drying either an aqueous solution containing the catalytic component elements or an aqueous dispersion of compounds containing said elements, to prepare a catalytic component composition.
(b) Calcining the catalytic component composition obtained in step (a), to prepare a calcined powder.
(c) Coating the calcined powder obtained in step (b) on an inactive carrier, together with a binder and a strength-improvers if necessary.
(3) A coated catalyst according to the above (2), wherein the rate of a supported-calcined powder based on the total of said carrier and the calcined powder supported in the step (c) is 15 to 50%.
(4) A catalyst or coated catalyst according to any of the above (1) to (3), wherein said catalytically active component composition is what is produced through a step of spray drying either an aqueous solution containing the catalytic component elements or an aqueous dispersion of compounds containing said elements.
(5) A coated catalyst according to any of the above (2) to (4), wherein said catalytically active component composition is what is obtained by using ceramic fiber for said strength-improver in the step (c).
(6) A coated catalyst according to any of the above (2) to (5), wherein said catalytically active component composition is what is obtained by using crystalline cellulose for said binder in the step (c).
(7) A catalyst or coated catalyst according to any of the above (1) to (6), which comprises being used in the process for the production of acrylic acid by vapor-phase catalytic oxidation of acrolein with molecular oxygen.
The present invention will be described in detail below, where “part” and “%” mean “part by mass” and “% by mass” respectively unless otherwise defined.
There is no limitation to antimony acetate used for the source material in the present invention. Antimony acetate available on the market is satisfactory to use. The purity etc. unless it damages catalytic activity, has no problem to be solved. Antimony acetate having a purity of 95% and more is generally used. One having a purity of 99% and more is more preferable.
The atomic ratios of the respective elements in a catalytically active component of the present invention, if they are within the ranges as described in the above formula (1), have no problem to be solved. The more preferable ranges in the formula (1) are 2≦a≦5, 0.2≦b≦2, 0.2≦c≦4, 0.3≦d≦4, 0≦e≦0.2, 0≦f≦0.5, 0≦g≦3. h, an atomic ratio of oxygen element, varies depending on atomic valences and atomic ratios of the other elements and is a value determined exclusively by the calcinations. The range is generally 42≦h≦133, preferably 43≦h≦75.
The catalyst of the present invention can be produced according to the conventional method for producing a molybdenum catalyst, except that antimony acetate is used for an antimony source material.
For example, at first, an aqueous solution contai

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