Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2002-05-13
2004-02-17
Nguyen, Cam N. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S327000, C502S328000, C502S330000, C502S332000, C502S335000, C502S349000, C502S355000, C502S415000, C502S439000
Reexamination Certificate
active
06693060
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a modified &thgr;-Al
2
O
3
-supported nickel reforming catalyst and its use for producing synthesis gas from natural gas. More particularly, the present invention is to provide a nickel reforming catalyst expressed by the following formula 1, having improved coke resistance, high-temperature catalysis stability and catalytic activity, which is prepared by coating nickel or mixture of nickel and cocatalyst (M
1
—M
2
—Ni) on a &thgr;-Al
2
O
3
support modified with metal (M
3
—M
4
—ZrO
2
/&thgr;-Al
2
O
3
), and its use for producing synthesis gas from natural gas through steam reforming, oxygen reforming or steam-oxygen reforming,
M
1
—M
2
—Ni/M
3
—M
4
—ZrO
2
/&thgr;-Al
2
O
3
(1)
wherein M
1
is an alkali metal; each of M
2
and M
3
is an alkaline earth metal; and M
4
is a IIIB element or a lanthanide.
BACKGROUND OF THE INVENTION
Steam reforming, which produces a mixture (synthesis gas) of hydrogen and carbon monoxide from methane (natural gas), has become an important and fundamental chemical industrial process from long time ago. Synthesis gas produced by steam reforming of methane is widely used for producing methanol, hydrogen, ammonia, etc. Recently, it has been used for producing liquid fuel or oxygen-including compounds.
The biggest problem in the steam reforming is deactivation of reforming catalyst due to deposition of carbon. The carbon deposition can be calculated thermodynamically from molar ratios of hydrogen to carbon and oxygen to carbon in the product. Therefore, in steam reforming of methane, excess amount of steam is required to increase molar ratios of hydrogen to carbon and oxygen to carbon, in order to prevent deactivation of reforming catalyst. This promotes an aqueous gasification enough to obtain a synthesis gas with molar ratio of hydrogen to carbon monoxide larger than 3:1. Therefore, this process may be suitable for producing ammonia or high-concentration hydrogen. The current industrial steam reforming process of methane is being carried out under the condition of 730-860° C. of a temperature, 20-40 atm of a pressure and 1:4-6 of methane-to-steam molar ratio.
And, for the industrial catalyst for the steam reforming, nickel catalyst is used D dominantly. A superior industrial reforming catalyst should have coke resistance and thermal and mechanical stability. For this purpose, selection of suitable support such as &agr;-alumina is very important.
The inventors suggested reforming reactions using modified zirconia-supported nickel catalyst [Korea Patent Application No. 99-50013; Korea Patent Application No. 2000-0054443; & Korea Patent Application No 2000-0057688]. Korea Patent Application No. 99-50013 discloses a modified zirconia-supported nickel catalyst and carbon dioxide reforming using it. Korea Patent Application No. 2000-0054443 discloses a cerium-modified zirconia-supported nickel catalyst and steam reforming using it. Further, Korea Patent Application No. 2000-0057688 discloses a modified zirconia-supported nickel catalyst and steam-oxygen reforming using it. The modified zirconia-supported nickel catalyst showed better activity and stability than those of conventional reforming catalysts when used in carbon dioxide reforming, steam reforming and steam-oxygen reforming even under severe condition (high space velocity and low steam-to-methane ratio) and at high temperature. Despite of good activity and stability, zirconia is not suitable to be used in reforming catalyst, because it is more expensive than alumina. Accordingly, it is required to use the more cost-effective &thgr;-Al
2
O
3
support and modify it with zirconia. Then, if it is coated with nickel catalyst, an inexpensive catalyst with good activity and stability can be obtained.
SUMMARY OF THE INVENTION
Inventors have developed a nickel reforming catalyst by coating &thgr;-Al
2
O
3
base support with zirconia modified with alkaline earth metal (M
3
) and IIIB element or lanthanide metal (M
4
), and coating nickel and alkali metal (M
1
) or alkaline earth metal (M
2
) cocatalyst. When this reforming catalyst was used in various reforming reactions of natural as, i.e., steam reforming, oxygen reforming or steam-oxygen reforming, it has showed equal or superior activity and stability compared with the modified zirconia-supported nickel catalyst we had suggested in Korea Patent Application No. 99-50013.
Accordingly, an object of the present invention is to provide a nickel reforming catalyst using &thgr;-Al
2
O
3
as base support, and its use for producing synthesis gas through reforming reaction.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is to provide a nickel reforming catalyst expressed by the following formula 1, which is used for producing synthesis gas mixture of carbon monoxide and hydrogen from natural gas,
M
1
—M
2
—Ni/M
3
—M
4
—ZrO
2
/&thgr;-Al
2
O
3
(1)
wherein M
1
, is an alkali metal; each of M
2
and M
3
is an alkaline earth metal; and M
4
is a IIIB element or a lanthanide.
Synthesis gas mixture of carbon monoxide and hydrogen may be produced from methane in the presence of the nickel reforming catalyst by steam reforming, oxygen reforming or steam-oxygen reforming, under the condition of 0-6 of methane-to-steam molar ratio, 0-1 of methane-to-oxygen molar ratio, 600-1000° C. of a reaction temperature, 0.5-20 atm of a reaction pressure and 1,000-1,000,000 cc/hr·g-cat of a space velocity.
Hereunder is given a more detailed description of the present invention. This invention relates to a reforming catalyst expressed by formula 1 and its use for producing synthesis gas by steam reforming, oxygen reforming or steam-oxygen reforming of natural gas.
The modified &thgr;-Al
2
O
3
-supported nickel reforming catalyst according to the present invention is prepared by coating a modified zirconia (M
3
—M
4
—ZrO
2
) on &thgr;-Al
2
O
3
base support and coating nickel and cocatalyst (M
1
—M
2
—Ni) on it. Here, nickel is added preferably in the range of 3 to 20 wt. % based to &thgr;-Al
2
O
3
. Each of M
1
and M
2
cocatalysts is added preferably in the range of 0 to 0.2 and 0 to 4 molar ratios based to nickel, respectively. Each of M
3
and M
4
is added preferably in the range of 0 to 1.0 and 0.01 to 1.0 molar ratios based to zirconium (Zr), respectively. Zirconia (ZrO
2
) is added preferably in the range of 0.01 to 1.0 molar ratio based to &thgr;-Al
2
O
3
.
M
1
is an alkali metal chosen from sodium, potassium and cesium; each of M
2
and M
3
is an alkaline earth metal chosen from calcium, magnesium and strontium, and M
4
is a IIIB element chosen from yttrium, lanthanum and cerium, or lanthanide, wherein M
3
and M
4
are cocatalysts for enhancing coke resistance and catalytic activity.
The reforming catalyst according to the present invention may be prepared by coprecipitation, precipitation, sol-gel method, molten-salt or impregnation method. &thgr;-Al
2
O
3
is modified with zirconia to obtain support, coprecipitation or sol-gel method is preferable. When nickel and cocatalyst are coated on the support, molten-salt and impregnation methods are preferable.
Preparation of modified &thgr;-Al
2
O
3
support through coprecipitation is as follows. 1 M zirconyl chloride aqueous solution is purified by recrystallization from hydrochloric acid. 1 M nitrate solution of the metal to be modified on the &thgr;-Al
2
O
3
base support is added to this solution. After strongly stirring the mixture at 50-70° C. for 4-8 hr, 29.8% ammonia water is added until pH reaches 10. The precipitate is filtered and washed with 5% ammonia water until no chloride ion is observed. It is further washed with distilled water. The filtered precipitate is placed in a drying oven and dried at 90-100° C. for 10-12 hr. Then, it is put in a furnace and calcined in 700-900° C. of air for 7-9 hr to obtain the modified &thgr;-Al
2
O
3
support.
Preparation of nickel- and cocatalyst-supported modified &thgr;-Al
2
O
3
support through impregnation is as follows. Modified (&thgr;-Al
2
O
3
support powder is added
Baek Seung-Chan
Baek Young-Soon
Choi Ri-Sang
Jun Ki-Won
Oh Young-Sam
Finnegan Henderson Farabow Garrett & Dunner LLP
Korea Research Institute of Chemical Technology
Nguyen Cam N.
LandOfFree
Modified &thgr;-Al2O3-supported nickel reforming catalyst... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Modified &thgr;-Al2O3-supported nickel reforming catalyst..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modified &thgr;-Al2O3-supported nickel reforming catalyst... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3322158