Combination of zeolite and alumina impregnated with a noble metal(s) for COS and THT removal at low temperatures (<40 degree C) in fuel cell processor applications

Abstract

The present invention is a process for removing sulfur-containing compounds from gaseous fuels and hydrocarbons, such as natural gas, at temperatures of less than about 100° C. The sulfur-contaminated feedstream is placed in intimate contact with a catalyst-sorbent which comprises a noble metal, a zeolite, and an alumina in a single reactor bed.

Description

BACKGROUND [0001] The present development is a method for removing sulfur-containing compounds from fluids, such as gaseous fuels and hydrocarbons. More specifically, the method comprises placing a feedstream in contact with a catalyst-sorbent which comprises a noble metal, a zeolite, and an alumina. The method is suitable for removing carbonyl sulfide and saturated heterocyclic sulfur compounds such as tetrahydrothiophene as well as thiols and hydrogen sulfide. [0002] The presence of sulfur compounds in fuels is problematic for a number of reasons. Burning such fuels produces sulfur oxides which are a form of pollution. Sulfur-laden exhaust also poisons the catalysts used to remove other harmful substances from the exhaust, resulting in additional pollution. Many of the catalysts used in refining and processing fuels are also subject to sulfur poisoning. The electrocatalysts used in fuel cells to extract energy from the fuel are highly sensitive to sulfur. Consequently, sulfur cont...

AI Technical Summary

Benefits of technology

[0014] The present invention is a process for removing sulfur-containing compounds, such as carbonyl sulfide, thiols, disulfides, and saturated heterocyclic sulfur compounds, including tetrahydrothiophene, from gaseous fuels and hydrocarbons, such as natural gas. The process includes at least a step in which a gaseous sulfur-contaminated feedstream is placed in contact with a catalyst-sorbent which comprises a noble metal, a zeolite, and an alumina in a single reactor bed. Use of a single bed reactor is advantageous when conserving space or weight is desirable. Further, the process is intended to operate at near-ambient temperature.

Problems solved by technology

The presence of sulfur compounds in fuels is problematic for a number of reasons.

Burning such fuels produces sulfur oxides which are a form of pollution.

Sulfur-laden exhaust also poisons the catalysts used to remove other harmful substances from the exhaust, resulting in additional pollution.

Many of the catalysts used in refining and processing fuels are also subject to sulfur poisoning.

Consequently, sulfur content in fuels used to power fuel cells must be rigorously restricted.

The removal of carbonyl sulfide (COS) is particularly troublesome because it is resistant to many desulfurization processes.

However, the process of the '653 patent relies on relatively high temperature and pressure, and requires hydrogen to be present in the process stream in order to effect sulfur compound removal.

Thus the process taught in the '907 patent uses zeolite and an alumina, but lacks a noble metal.