Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By dehydrogenation
Reexamination Certificate
2000-02-17
2001-12-25
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By dehydrogenation
C562S544000, C562S548000, C560S241100, C560S243000, C502S305000, C502S311000, C502S312000, C502S317000, C502S344000
Reexamination Certificate
active
06333444
ABSTRACT:
The present invention relates to a catalyst for the oxidation of ethane to ethylene and/or acetic acid and/or for the oxidation of ethylene to acetic acid, and to a process for the production of acetic acid and/or ethylene utilising the aforesaid catalyst. Catalysts comprising molybdenum, vanadium and niobium in combination with oxygen for use in processes for the production of acetic acid by the oxidation of ethane and ethylene are known in the art from, for example, U.S. Pat. No. 4,250,346.
U.S. Pat. No. 4,250,346 discloses the oxidative dehydrogenation of ethane to ethylene in a gas phase reaction at relatively high levels of conversion, selectivity and productivity at a temperature less than 500° C. using as catalyst a composition comprising the elements molybdenum, X and Y in the ratio Mo
a
X
b
Y
c
wherein X is Cr, Mn, Nb, Ta, Ti, V and/or W, and preferably Mn, Nb, V and/or W; Y is Bi, Ce, Co, Cu, Fe, K, Mg, Ni, P, Pb, Sb, Si, Sn, Tl and/or U, and preferably Sb, Ce and/or U, a is 1, b is 0.05 to 1.0 and c is 0 to 2, and preferably 0.05 to 1.0, with the proviso that the total value of c for Co, Ni and/or Fe is less than 0.5.
WO 99/20592 to Celanese relates to a method of selectively producing acetic acid from ethane, ethylene or mixtures thereof and oxygen at high temperature in the presence of a catalyst having the formula Mo
a
Pd
b
X
c
Y
d
wherein X represents one or several of Cr, Mn, Nb, Ta, Ti, V, Te and W; Y represents one or several of B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Nb, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl and U and a=1, b=0.0001 to 0.01, c=0.4 to 1 and d=0.005 to 1.
German patent application DE 196 30 832 A1 relates to a similar catalyst composition in which a=1, b>0, c>0 and d=0 to 2. Preferably, a=1, b=0.0001 to 0.5, c=0.1 to 1.0and d=0 to 1.0.
The catalysts of both WO 99/20592 and DE 19630832 require the presence of palladium.
WO 98/47850 relates to a process for producing acetic acid from ethane, ethylene or mixtures thereof and a catalyst having the formula W
a
X
b
Y
c
Z
d
in which X represents one or several of Pd, Pt, Ag and Au, Y represents one or several of V, Nb, Cr, Mn, Fe, Sn, Sb, Cu, Zn, U, Ni, and Bi and Z represents one or several of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, Hf, Ru, Os, Co, Rh, Ir, B, Al, Ga, In, Tl, Si, Ge, Pb, P, As and Te, a=1, b>0, c>0 and d is 0 to 2.
The catalyst of WO 98/47850 does not contain molybdenum.
WO 99/51339 relates to a catalyst composition for the selective oxidation of ethane and/or ethylene to acetic acid which composition comprises in combination with oxygen the elements Mo
a
W
b
Ag
c
Ir
d
X
e
Y
f
wherein X is the elements Nb and V; Y is one or more elements selected from the group consisting of Cr, Mn, Ta, Ti, B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Cu, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl, U, Re and Pd; a, b, c, d, e and f represent the gram atom ratios of the elements such that 0<a≦1, 0≦b<1 and a+b=1; 0<(c+d)≦0.1; 0<e≦2; and 0≦f≦2.
There remains a need for catalyst for the oxidation of ethane to ethylene and/or acetic acid and/or for the oxidation of ethylene to acetic acid and a process for the production of acetic acid and/or ethylene employing the catalyst.
We have found that oxidation catalysts comprising molybdenum, vanadium and niobium in combination with oxygen which employ gold as an essential component in the absence of palladium can fulfill the need for an oxidation catalyst and process employing same.
Accordingly, the present invention provides a catalyst composition for the oxidation of ethane to ethylene and/or acetic acid and/or for the oxidation of ethylene to acetic acid which composition comprises in combination with oxygen the elements molybdenum, vanadium, niobium and gold in the absence of palladium according to the empirical formula:
Mo
a
W
b
Au
c
V
d
Nb
e
Y
f
(I)
wherein Y is one or more elements selected from the group consisting of: Cr, Mn, Ta, Ti, B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl, U, Re, Te, La and Pd; a, b, c, d, e and f represent the gram atom ratios of the elements such that:
0<a≦1; 0≦b<1 and a+b=1;
10
−5
<c≦0.02;
0<d≦2;
0<e≦1; and
0<f≦2.
Catalysts embraced within the formula (I) include:
Mo
a
W
b
Au
c
V
d
Nb
e
Y
f
Mo
a.
Au
c
V
d
Nb
e
Y
f
Mo
a
W
b.
Au
c
V
d
Nb
e
Mo
a.
Au
c
V
d
Nb
e
Examples of suitable catalysts having the formula (I) include: Mo
1.00
V
0.25
Nb
0.12
Au
0.01
O
y
; Mo
1.00
V
0.213
Nb
0.138
Au
0.007
O
y
; Mo
1.00
V
0.232
Nb
0.139
Au
0.007
O
y
; and Mo
1.000
V
0.426
Nb
0.115
Au
0.0008
O
y
wherein y is a number which satisfies the valencies of the elements in the composition for oxygen.
Preferably a>0.01. Preferably, d>0.1. Preferably, e>0.01. Preferably, e≦0.5. Preferably, f≧0.01. Preferably, f≦0.5.
Preferably, Y is selected from the group consisting of Bi, Ca, Ce, Cu, K, P, Sb, La and Te.
An advantage of catalyst compositions according to the present invention is that they can be more active and selective in converting ethane and/or ethylene to acetic acid and/or ethylene.
The catalyst compositions may be prepared by any of the methods conventionally employed for the preparation of catalysts. Suitably the catalyst may be prepared from a solution of soluble compounds and/or complexes and/or compounds of each of the metals. The solution is preferably an aqueous system having a pH in the range from 1 to 12, preferably from 2 to 8, at a temperature of from 20° to 100° C.
Generally, a mixture of compounds containing the elements is prepared by dissolving sufficient quantities of soluble compounds and dispersing any insoluble compounds so as to provide a desired gram-atom ratio of the elements in the catalyst composition. The catalyst composition may then be prepared by removing the solvent from the mixture. The catalyst may be calcined by heating to a temperature of from 200 to 550° C., suitably in air or oxygen, for a period of from 1 minute to 24 hours. Preferably, the air or oxygen is slowly flowing.
The catalyst may be used unsupported or supported. Suitable supports include silica, alumina, zirconia, titania, silicon carbide and mixtures of two or more thereof.
Further details of a suitable method for preparing a catalyst composition may be found in, for example, EP-A-0166438.
The catalyst may be used in the form of a fixed or a fluidised bed.
In another embodiment the present invention provides a process for the production of ethylene and/or acetic acid from a gaseous mixture comprising ethane and/or ethylene which process comprises contacting the gaseous mixture with a molecular oxygen-containing gas at elevated temperature in the presence of a catalyst composition as hereinbefore described.
Ethane is oxidised to ethylene and/or acetic acid and/or ethylene is oxidised to acetic acid. Preferably, ethane and optional ethylene is oxidised to a mixture comprising ethylene and acetic acid which may be used with or without the addition or removal of acetic acid and/or ethylene for the production of vinyl acetate by reaction with a molecular oxygen-containing gas in an integrated process.
The feed gas comprises ethane and/or ethylene, preferably ethane.
Ethane and/or ethylene may be used in substantially pure form or admixed with one or more of nitrogen, methane, carbon dioxide and water in the form of steam, which may be present in major amounts, for example greater than 5 volume percent or one or more of hydrogen, carbon monoxide, C
3
/C
4
alkenes and alkenes, which may be present in minor amounts, for example less than 5 volume percent.
The molecular oxygen-containing gas may be air or a gas richer or poorer in molecular oxygen than air, for example oxygen. A suitable gas may be, for example, oxygen diluted with a suitable diluent
Ellis Brian
Jones Michael David
BP Chemicals Limited
Griffin Walter D.
Nixon & Vanderhye
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