Abstract: A refinery catalyst is regenerated by burning off coke in an air stream to give an off-gas: before cryogenic recovery of hydrocarbons from the off-gas, nitrogen oxides (NOx) are removed from the off-gas by contact with a hydrogenation catalyst.

Abstract: The absorption capacity of a desulphurizing absorbent bed is increased by temporarily increasing the temperature of the absorbent bed by at least 50.degree. C. from the normal operating temperature to a maximum temperature not in an excess of 500.degree. C.

Abstract: Desulphurization process for feedstocks in which the sulphur compounds contained therein are first separated into a concentrate stream which is then hydro-desulphurized, and the resulting hydrogen suphide removed using conventional sulphur removal techniques. The initial separation is preferably effected using membrane separation or temperature swing absorption processes.

Abstract: Carbon dioxide containing gas streams are desulphurised at below 100.degree. C. using high surface area, high porosity, agglomerates containing copper oxide, and zinc oxide and/or an oxide of another element such as aluminium.

Abstract: Desulphurization of a feedstock using a regenerable sorbent to give a desulphurized stream, regeneration of the sorbent by heating, feedstock, and during at least the initial part of the cooling, at least part of the effluent from the sorbent is contacted with a non-regenerable particulate sorbent. The desired desulphurized product comprises the effluent from the regenerable sorbent that has bypassed the particulate sorbent.Preferably the heat for regeneration is obtained by heat exchange with the products of combustion of the sulphur laden regeneration fluid.In an alternative process using a particulate sorbent for a "polishing" operation, the regenerable sorbent is replaced by a membrane separation unit giving a desulphurized stream and a sulphur laden stream, which is combusted to heat, by heat exchange, the desulphurized stream before it passes through the particulate sorbent.

Abstract: Desulphurization of natural gas is effected using a bed of particulate adsorbent comprising zinc oxide at below 30.degree. C. before molecular sieve drying of the gas. The absorbent particles preferably have a high BET surface area and pore volume.