Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2002-10-31
2003-10-28
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S202000, C502S204000, C502S205000, C502S206000, C502S208000, C502S209000, C502S210000, C502S211000, C502S212000, C502S232000, C502S240000, C502S244000, C502S246000, C502S247000, C502S248000, C502S249000, C502S254000, C502S255000, C502S258000, C502S259000, C502S260000, C502S263000, C502S302000, C502S303000, C502S304000, C502S305000, C502S306000, C502S307000, C502S308000, C502S309000, C502S310000, C502S311000, C502S312000, C502S317000, C502S318000
Reexamination Certificate
active
06638890
ABSTRACT:
1. Field of Industrial Utilization
This invention relates to catalyst carrier, complex oxide catalyst and production process of acrylic acid. More particularly, the invention relates to a modified carrier suitable as a carrier of a catalyst for making acrylic acid from acrolein by vapor phase catalytic oxidation reaction, a catalyst formed by supporting a complex oxide catalyst on said modified carrier, and to a producing process of acrylic acid using said catalyst.
2. Prior Art
A large number of improved catalysts for preparing acrylic acid through vapor phase catalytic oxidation reaction of acrolein have been proposed. For example, Japanese Patent Publication No. 12129/69 described a catalyst formed of molybdenum, vanadium and tungsten; Publication No. 11371/74, that formed of molybdenum, vanadium, copper, tungsten and chromium; Publication No. 25914/75, that formed of molybdenum and vanadium; and Laid-open (Kokai) Patent Application, Kokai No. 85091/77, that formed of molybdenum, vanadium, copper and at least one element of antimony and germanium.
However, these conventional catalysts are not fully satisfactory for industrial working, because of such defects that the yield of the object product, i.e., acrylic acid, is insufficient and deterioration rate in activity is high, leading to short catalyst life. Therefore, development of catalysts which excel in stability and enable acrylic acid production at high yield over prolonged periods has been in demand.
[Problem to Be Solved by the Invention]
Accordingly, one of the objects of the present invention is to provide a carrier, in particular, a novel carrier suitable for use in production of acrylic acid through vapor phase catalytic oxidation of acrolein.
Another object of the invention is to provide a complex oxide catalyst, in particular, a complex oxide catalyst which is suitable for producing acrylic acid through vapor phase catalytic oxidation of acrolein.
A further object of the present invention is to provide a process for preparing acrylic acid at high yield over prolonged periods, by oxidizing acrolein in the presence of catalyst at vapor phase with molecular oxygen or a molecular oxygen-containing gas.
[Means to Solve the Problem]
We have discovered that a product obtained by having a commonly used inert carrier carry an oxide containing at least an element selected from alkaline earth metals, at least an element selected from silicon, aluminum, zirconium and titanium, and optionally at least an element selected from Group IA elements and Group IIIb elements of the periodic table, boron, iron, bismuth, cobalt, nickel and manganese on at least a part of its surface (which product is hereafter referred to as a modified carrier) is useful as a carrier of the oxidation catalyst; and that the use of, for example, a product which is obtained by having the modified carrier carry a complex oxide containing molybdenum and vanadium(which product is hereafter referred to as a complex oxide catalyst) as the catalyst in the oxidation reaction of acrolein enables production of acrylic acid in high yield stably over prolonged periods.
Thus, according to the invention, a modified carrier is provided, which is characterized in that an inert carrier is caused to carry, on at least a part of its surface, an oxide expressed by the formula (1):
X
a
Y
b
Z
c
O
d
(1)
(where X is at least an element selected from alkaline earth metals, Y is at least an element selected from silicon, aluminum, titanium and zirconium, Z is at least an element selected from Group IA elements and Group IIIb elements of the periodic table, boron, iron, bismuth, cobalt, nickel and manganese, and O is oxygen; a, b, c and d denote the atomic ratios of X, Y, Z and O, respectively; and where a=1, 0<b≦100 (preferably 0.01≦b≦100), 0≦c≦10, and d is a numerical value determined by the extents of oxidation of the other elements).
According to the invention, also a complex oxide catalyst characterized by having a complex oxide containing molybdenum and vanadium, in particular, a complex oxide which is expressed by the following general formula (2):
Mo
e
V
f
W
g
Cu
h
A
i
B
j
O
k
(2)
(where Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, A is at least an element selected from antimony, niobium and tin, B is at least an element selected from phosphorus, tellurium, lead, arsenic and zinc, and O is oxygen; e, f, g, h, i, j and k denote atomic ratios of Mo, V, W, Cu, A, B and O, respectively; and where e is 12, 2≦f≦15, 0≦g≦10, 0<h≦6 (preferably 0.01≦h≦6), 0≦i≦6, 0≦j≦5, and k is a numerical value determined by the extents of oxidation of the other elements), carried on said modified carrier is provided.
According to the invention, furthermore, a process for preparation of acrylic acid by oxidizing acrolein at vapor phase with molecular oxygen or a molecular oxygen-containing gas in the presence of a catalyst is provided, the process being characterized by the use of said complex oxide catalyst as the catalyst.
[Embodiments of the Invention]
As the inert carrier, any of those generally used for preparation of various catalysts, in particular, catalysts for oxidation of acrolein, can be used, the typical ones being silica, alumina, silica-alumina, silicon carbide, silicon nitride, titanium dioxide, zirconium oxide and the like. Of those alumina and silica-alumina are the preferred.
The modified carrier of the invention is formed by having such an inert carrier carry on at least a part of its surface an oxide represented by the general formula (1). That is, the modified carrier of the invention is formed of an inert carrier and an oxide of the general formula (1) which is carried on at least a part of the surface of the inert carrier. The form of the oxide of the general formula (1) which is carried on the inert carrier is subject to no critical limitation, but it is normally preferred that an effective amount of the oxide covers the inert carrier with an approximately uniform thickness.
The amount of the oxide of the general formula (1) which is to be carried on the inert carrier is such that can at least exhibit sufficient carriage effect. More specifically, it is satisfactory to have the inert carrier carry thereon an oxide of the general formula (1) at a carriage ratio of 1-50%, preferably 3-30%, said ratio being calculated by the following equation:
carriage ratio (%)=[1-(weight of inert carrier/weight of modified carrier)]×100.
Where the carriage ratio is less than 1%, the effect of the modified carrier cannot be sufficiently obtained. Whereas, when it exceeds 50%, the surface properties of the inert carrier itself such as coarseness and porosity are impaired by the supported oxide, to reduce adhesion between the modified carrier and the catalytic component supported thereon, giving rise to such a problem as peel-off of the catalyst component.
The condition of carriage of the oxide of the general formula (1) on the inert carrier surface in the modified carrier of the invention can be confirmed by means of a linear or planar analysis of cross-section with EPMA (Electron Probe Micro Analyzer).
Among the oxides which are expressed by the general formula (1), those whose X-component is magnesium, calcium, strontium or barium; Y-component is silicon or aluminum; Z-component is sodium, potassium, iron, cobalt, nickel or boron; and where a=1, 0<b≦100 (preferably 0.01≦b≦100) and 0≦c≦10, are preferred.
The modified carrier of the invention can be prepared following the generally practiced methods for having an inert catalyst carry the substance to be supported. For example, compounds containing at least an element selected from alkaline earth metals; at least an element selected from silicon, aluminum, zirconium and titanium; and optionally at least an element selected from Group IA elements and Group IIIb elements of the periodic table, boron, iron, bismuth, cobalt, nickel and manganese are carried and d
Nakamura Daisuke
Tanimoto Michio
Yunoki Hiromi
Nippon Shokubai Co. , Ltd.
Sherman & Shalloway
Wood Elizabeth D.
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