JPS6082137A - Reforming catalyst of methanol - Google Patents

Abstract

PURPOSE:To obtain a titled catalyst having high activity at low temp. and long life whereby H2 and CO are produced highly selectively by depositing at least one kind of noble metal on the alumina carrier previously covered with zinc oxide and/or chromium oxide. CONSTITUTION:At least one kind of noble metal such as platinium and Pd is deposited on the alumina carrier previously covered with zinc oxide and/or chromium oxide. The amount of zinc oxide and/or chromium oxide covering the alumina carrier is preferably within the range of 0.05-50wt%. The deposited amount of at least one kind of noble metal such as platinium and Pd is preferably within the range of 0.01-10wt%. The catalyst obtained by said process is highly selective for the reaction wherein methanol is decomposed to the gas containing H2 and CO, and is highly active and has extremely excellent durability.

Description

[Detailed description of the invention] The present invention is directed to a catalyst for reforming methanol and alcohol.

More specifically, in a method for reforming methanol into a gas containing hydrogen and carbon monoxide, the present invention selectively generates water and carbon monoxide, and provides a highly active and long-life catalyst at low temperatures.

Methanol can be produced on a large scale from coal, natural gas, etc. via synthetic gas, and is easy to transport, so it is of great interest in the future as an energy source to replace petroleum or as a raw material for various chemical industries. is leaning.

One method of using it is to decompose methanol into a gas containing hydrogen and carbon monoxide, and use this as a non-polluting fuel for automatic military use or as a raw material for producing reducing gas.

On the other hand, hydrogen is separated from this cracked gas, and this hydrogen, t-
It can be used as a fuel for fuel cell power generation, and as a water molasses for making frozen confectionery from various organic compounds at Sekishu Koka.
-E carbon can also be used in the carbonylation process of various organic compounds.

Thermodynamically, the decomposition reaction of methanol can occur at relatively low temperatures, but the presence of a catalyst is essential to make it economical.

Conventionally, catalysts for decomposing methanol have been proposed in which platinum metal elements such as platinum or base metal elements such as copper, nickel, chromium, zinc, and their oxides are supported on a carrier such as alumina (hereinafter referred to as Al2O3). Although,
These catalysts still have many problems to date, such as poor low-temperature activity, lack of heat resistance, and short lifespan.

Among the above conventional catalysts, for example, r -AJ? A problem with the catalyst in which platinum is supported on 203 is that it tends to cause not only the desired reaction described below, but also the following side reaction (2) in which methane, carbon dioxide, water, ether, aldehyde, etc. are produced.

Reaction ■ OHOH-1→00 + 2H2 Reaction CH30H+ H2--→CH4+H2O0H30H+
C10--→CH4+0020H30H-1→aa3
oaH3+34H2゜0H30H--→C0H2+H2
0 Of the above reactions, ■ is the main reaction of methanol decomposition, and the decomposition gas generated at this time is the endothermic fluorescent phase of the decomposition reaction (approximately 22
This has the advantage that the exothermic power of the cracked gas increases by Kcal/mol), leading to improved thermal efficiency.

However, if a side reaction such as reaction (2) occurs, this reaction is an exothermic reaction, and therefore results in a loss in terms of thermal efficiency.

Indeed, when this cracked gas is used to produce hydrogen in various processes, the water and ethers produced as by-products of the reaction pose a national problem in separation and purification.

Furthermore, among reactions (2), the carbon production reaction causes deterioration of the catalyst or clogging of the actuator, which impedes long-term stable operation.

Therefore, in order to solve the above problem, the present inventors interposed a third substance between alumina and an active metal. In other words, zinc oxide or chromium oxide was supported on alumina in advance, and it usually acts as an acidic catalyst. γ-A120
Focusing on the fact that side reactions can be suppressed by converting 5 into basic properties and causing a dehydrogenation reaction, we conducted various experimental studies and found that alumina has the ability to suppress side reactions in advance. It was discovered that a catalyst coated with zinc oxide or chromium oxide and on which noble metals such as platinum and palladium are supported has extremely excellent activity and selectivity in the methanol decomposition reaction, and in completing the present invention. It's arrived.

That is, the present invention relates to a catalyst for methanol decomposition, characterized in that one or more noble metals such as platinum and palladium are supported on an alumina carrier coated in advance with zinc oxide and/or chromium oxide.

The amount of zinc oxide and/or chromium oxide that coats the alumina support is preferably in the range of 0.05 to 50% by weight, and the amount of one or more noble metals such as platinum and palladium supported is 0.0%.
A range of 1 to 10% by weight is preferred.

Here, coating alumina with zinc oxide and/or chromium oxide can be easily obtained by immersing alumina in an aqueous solution of zinc and/or chromium nitrate and then firing.

Next, the method of supporting the noble metal on the carrier thus obtained can be any conventional method without any problems, such as nitrate or chloride of the noble metal.

A method is applied in which the carrier is immersed in an aqueous solution of a compound such as an ammine complex, calcined, and then treated with hydrogen reduction.

The catalyst obtained as described above has high selectivity and activity (and extremely high durability) for the reaction that decomposes methanol into gases containing hydrogen and carbon monoxide. It is.

Hereinafter, the present invention will be specifically explained with reference to Examples.

[Example 1] Pellets made of γ-A/203 with a particle size of 2 to 4 μm were immersed in an aqueous solution of zinc nitrate, dried, and calcined at 350°C for 6 hours to reduce ZnO to 5% by weight based on alumina. A supported carrier was obtained.

The carrier thus obtained was immersed in an aqueous solution of tetraammine diplatinum chloride (Pt(NH,)4c/2).

After drying, it was fired at 500°C for 3 hours to support 0.5% by weight of platinum, and then at 400°C for 6 hours.

Catalyst 1 was prepared by reduction in a 4% hydrogen stream.

This catalyst 1 was subjected to an activity evaluation test under the conditions shown in Table 1, and the results shown in Table 1 and Table 2 were obtained.

As a comparative catalyst, a conventional catalyst in which 0.5% by weight of platinum was supported on 411 pieces of alumina was prepared, and an activity evaluation test was conducted under the conditions shown in Table 1 (however, only at a reaction temperature of 400° C.). The results are also shown in Table 2.

Table 1 Table 2 [Example 2] In Example 1, I! In the same manner as Catalyst 1 prepared by
The concentration of O is 0.2, 1.0 and 5.0%, respectively.
Samples 1IX2-6 were prepared in which platinum was supported at a concentration of 10% by weight, and platinum was supported at 0.3% by weight by using an aqueous solution of chloride and hydrogen reduction treatment.

These catalysts were subjected to activity evaluation tests under the conditions shown in Table 1 of Example 10, except that the reaction temperature was 400C, and the results shown in Table 3 were obtained.

Table 3 [Example 3] Alumina-Cr2O3 carrying 5% ar2O3
The carrier has a platinum concentration of 0.1.0.3.0.5.1%.
Catalysts 7 to 10 were supported so that the palladium concentration was 0.1.0.5% by weight, and Catalyst 11.
I made 12 myself. Also, ZnO and 0r203f each 5X
Catalyst 13'j in which 0.5% by weight of platinum was supported on an alumina-2,0.Cr2O3 carrier supported by a lid%.
t was prepared.

Regarding these catalysts 7 to 13, an activity evaluation test was conducted under the conditions shown in Table 1 of Example 10, except that the reaction source K was changed to 400C, and the results shown in Table 4 were obtained.

Table 4 [Example 4] 1 ton of catalyst made by W/IJ in Example 1 - 5 cc was filled in a stainless steel reaction tube, and methanol was heated to 5C at 400C.
A continuous test was carried out for 800 hours by continuously serving C/h.

As a result, it was confirmed that there was almost no change in the methanol reaction rate and cracked gas composition from the initial stage, and that there was no carbon precipitation on the catalyst surface.

[Example 5] In catalyst 1 of Example 1, γ-AI! A catalyst j4t supported with 0.5% heavy charge of platinum was prepared in the same manner except that α-A/203t was used instead of 2030, and an activity evaluation test was conducted in the same manner as in Example 1. The same performance was obtained.

The above examples were conducted using granular catalysts, but
The shape of the catalyst is not particularly limited, and may be honeycomb,
Needless to say, it may be used in a shape such as a plate.

Furthermore, although the above examples were carried out using methanol alone, it is also possible to carry out the methanol fraction M in the coexistence of a gas containing water vapor, air, or the like.

Among the sub-agents: 1) Akira Sub-agent Hagi Hara Kaji -

Claims (1)

[Claims] A catalyst for methanol reforming that is based on a carrier coated with alumina in advance with zinc oxide and/or chromium oxide, with at least one amount of a noble metal supported thereon.