Extrusion of silica-rich solids

Abstract

The present invention is directed to a method for extruding silica-rich solids. The method comprises mixing silica-rich solids with water in an alkali metal base or basic salt followed by mulling and extruding and subsequently drying the extrudate whereby the dried extrudate has a crush strength superior to that of the prior art. The silica-rich solids can be silica alone, zeolite alone or a mixture thereof. The alkali metal can be sodium hydroxide. The invention is also directed to a product which has a special attribute in that they have sufficient integrity to withstand treatments with acids so that it is now possible to steam, acid extract, or calcine such extrudates. The catalyst can be used in hydrocarbon conversions such as hydrocracking, isomerization, hydrogenation, dehydrogenation, polymerization, reforming, catalytic cracking, or catalytic hydrocracking. The invention also relates to a method for extruding silica-rich solids which comprises substituting an alkali metal for hydrogen in silanol groups on outside surfaces of the silica-rich solids, mulling and extruding the substituted silica-rich solids and drying the extrudate whereby the dried extrudate has a crush strength superior to that of the prior art. The invention is also directed to a method for increasing the silica to metal ratio of a zeolite. The method comprises mixing silica-rich solids with water and an alkali metal base or basic salt, mulling and extruding the silica-rich mixture, drying the extrudate, ion exchanging the extrudate and recovering the catalyst which can be substantially metal free.