| 摘要 |
Catalyst comprises a porous support grain on which palladium and silver are deposited, and at least one metal comprising alkali or alkaline earth metal. The porous support comprises at least one refractory oxide comprising silica, alumina or silica-alumina. The specific surface area of the porous support is 10-150 m 2>/g. In the catalyst, and the palladium content is 0.05-0.6 wt.% and the silver content is 0.02-3 wt.%. Catalyst comprises a porous support grain on which palladium and silver are deposited, and at least one metal comprising alkali or alkaline earth metal. The porous support comprises at least one refractory oxide comprising silica, alumina or silica-alumina. The specific surface area of the porous support is 10-150 m 2>/g. In the catalyst, and the palladium content is 0.05-0.6 wt.% and the silver content is 0.02-3 wt.%. At least 80 wt.% of the palladium is distributed in a crust at the periphery of the support, where the thickness of the crust is 10-160 mu m. At least 80 wt.% of the silver is distributed in a crust at the periphery of the support, where the thickness of the crust is 10-160 mu m. The local content of palladium at each point along the diameter of the grain follows the same course as the local content of silver. The sum of the contents of alkali and/or alkaline earth metals is 0.02-5 wt.%. Independent claims are also included for: (1) preparing the catalyst comprising: introducing the palladium onto the support, comprising (a1) preparing a colloidal suspension of palladium oxide or palladium hydroxide in an aqueous phase by mixing an aqueous solution-1 comprising at least one hydroxide which is alkali hydroxide or alkaline earth hydroxide and an aqueous solution-2 comprising at least one palladium precursor, through pouring the solution-2 and then the solution-1 into the apparatus or pouring the solutions 1 and 2 simultaneously into the apparatus, (a2) impregnating the colloidal suspension onto the porous support grain having a specific surface area of 10-150 m 2>/g, (a3) maturing the obtained impregnated support and (a4) drying and calcining the obtained catalyst; and introducing the silver, comprising (b1) reducing the catalyst by placing it in contact with an aqueous solution comprising at least one liquid phase reducing agent, (b2) filtering the catalyst, (b3) impregnating the catalyst by placing it in contact, under agitation, with an aqueous solution comprising a silver precursor salt, (b4) filtering and drying the catalyst and (b5) calcining the catalyst, preferably at 450-700[deg] C; and (2) selective hydrogenation comprising bringing a feed into contact with the catalyst, where the feed is 3-5C steam-cracking and/or catalytic-cracking cuts or steam-cracking gasolines. |
