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Keywords:

n-decane hydroisomerization, heteropoly acids, sba-15 synthesis, tungsten phosphoric acid, bifunctional catalysis, mesoporous silica sba-15, supported 12-tungstophosphoric acid, solid acid, skeletal isomerization, catalytic-activity, thermal-stability, sulfated zirconia, y zeolites, sipw-x, h3pw12o40, Science & Technology, Physical Sciences, Technology, Chemistry, Physical, Engineering, Chemical, Chemistry, Engineering, n-Decane hydroisomerization, Heteropoly acids, SBA-15 synthesis, Tungsten phosphoric acid, Bifunctional catalysis, SOLID ACID, MESOPOROUS SILICA, 12-TUNGSTOPHOSPHORIC ACID, SKELETAL ISOMERIZATION, CATALYTIC-ACTIVITY, THERMAL-STABILITY, SULFATED ZIRCONIA, H3PW12O40, IMMOBILIZATION, HYDROISOMERIZATION, 0306 Physical Chemistry (incl. Structural), 0904 Chemical Engineering, Physical Chemistry, 3402 Inorganic chemistry, 3406 Physical chemistry, 4004 Chemical engineering

Abstract:

SBA-15 ordered mesoporous silica materials containing up to 40 wt.% of HPW heteropoly acid were synthesized via an original method involving the introduction of HPW in an acidified solution of P123 triblock copolymer (EO20PO70O20), the SBA-15 mesostructuring agent (direct synthesis). Samples with similar HPW loadings were also prepared by impregnation of SBA-15. Characterization by XRD, P-31 MAS NMR, NH3-TPD, and N-2 adsorption showed that even after calcination HPW in the direct synthesis samples was better dispersed than that in the impregnated samples. SBA-15-supported HPW materials were converted into bifunctional catalysts. In the conversion of n-decane, direct synthesis samples were superior to impregnated samples. The criteria of ideal bifunctional catalysis were fulfilled, e.g. high yields of skeletal isomers (>70%), of multi-branched skeletal isomers, and of branched cracked products, and hydrocracking reactions limited to primary cracking. Compared to ultrastable Y zeolites, the HPW/SBA-15 samples showed a broader optimum reaction temperature window for isomerization and higher n-decane dibranching selectivity. (C) 2009 Elsevier Inc. All rights reserved.