TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The core carrier material is porous with a total pore volume of at most 1% of the total core carrier material.The metal precursor is a metal oxide or a water-soluble metal salt, especially a chloride, nitrate, 1-10C carboxylate, carbonate, bicarbonate, sulfate, hydrogen sulfate or phosphate.The shell thickness is 1-1,000 (especially 50-300) microns and different layers of composite shells may contain different catalytically-active metals and/or different concentrations of such metals.Catalyst Preparation: Catalyst preparation comprises:(a) sprinkling the inert core material with an oxidic powdered carrier material to form a shell;(b) spraying with a liquid binder comprising an aqueous solution of an organic compound having a boiling or sublimation temperature above 100 degreesC at normal pressure;(c) introducing a catalytically-active Group 10 or 11 metal or metal precursor;(d) evaporating the volatiles and optionally(e) activating the precursor, with steps (a), (b) and (c) being carried out simultaneously or in any suitable order and optionally being repeated.The catalytically-active metal or precursor can be distributed in the powdered form binder or can be dissolved or suspended in the binder.Prior to step (a) a carrier is coated with a layer of dry powdered carrier material, this then being wetted with binder.Following step (d) the catalyst is calcined at 200-600 degreesC. EXAMPLE - A catalyst showing a 57% selectivity for ethylene in hydrogenation of a 90/10 volume mixture of ethylene and acetylene to give 90% acetylene conversion at 85 degreesC with H2 : acetylene ratio 1.8 : 1 and GHSV 3,000 l/hour was obtained by coating 2.503 mm diameter non-porous steatite spheres (500 g) with Versal(TM) ( alumina calcined at 1050 degreesC for 5 hours) (100 g) with parallel addition of a solution of glycerol as binder together with Ag (0.045 g) as AgNO3 and Pd (0.0925 g) as a solution of Pd nitrate in HNO3, followed by drying and calcining at 300 degreesC. In a control using a prior-art catalyst of similar materials but lacking the steatite core the selectivity was 25% at 100 degreesC for 90% acetylene conversion.