High surface purity heat transfer solids for high temperature fluidized bed reactions

Abstract From the Canadian patent

High surface purity heat transfer solids are formed suitably, by washing and treating particulate refractory inorganic solids notably alumina, which contains as impurities up to about 0.5 wt% silicon and/or up to about 500 wppm boron with an acid, or dilute, acid solution sufficient to reduce the concentration of silicon and boron in the outer peripheral surface layer of the particles e.g. as, measured inwardly toward the center of a particle to a depth of about 50.ANG. using X-ray photoelectron spectroscopy to no greater than about, atom % silicon and boron preferably about 2 atom % silicon and, boron based on the total number of cations within said outer peripheral surface layer, thereby …