Characterization of CrAPO-5 Materials in Test Reactions of Conversion of 2-Methyl-3-butyn-2-ol and Isopropanol

CrAPO-5 materials with various amounts of Cr(III) stably incorporated into the framework positions were tested in the reactions of conversion of 2-methyl-3-butyn-2-ol (MBOH) and isopropanol. The results were compared with those obtained over similar materials containing extraframework chromium species and over nonsubstituted AlPO4-5. The products of the reactions indicated an increased acidity of catalytic sites in CrAPO-5 compared to that in AlPO4-5. The yield of conversion depends mainly on the amount of chromium and its distribution. The multivalent extraframework Cr species yielded similar catalytic effects as framework Cr centers. However, their activity dropped very quickly due both to the hindrances to alcohol molecules in accessing the catalytic sites in the pores clogged by these species and to the faster coking.