Effect of support composition on the activity of Pt and PtMo catalysts in the conversion of n-hexadecane

• Investigated were Pt(1%) and Pt(1%)Mo(4–8%) catalysts for n-C16 conversion.
• The catalysts supported on AlSBA-15 are more active than these on SiO2Al2O3.
• Pt(1%)Mo(8%)/AlSBA-15 provided the highest iso/n ratio within the cracking products.
• PtMo/AlSBA-15 displayed weaker Mo–support interactions than PtMo/SiO2Al2O3.

The SiO2Al2O3 material and mesoporous molecular sieves of AlSBA-15 type described in this work were applied as the supports for the Pt and PtMo catalysts. Catalysts were synthesized by one step impregnation, i.e. Pt catalysts with 1 wt.% of Pt as well as by two step impregnation, i.e. PtMo catalysts with 4–8 wt.% of Mo followed by 1 wt.% of Pt. The activity of the catalysts was investigated in n-C16 conversion (5 MPa; 320–370 °C; WSHV, 3.5 h−1; H2:CH, 350:1 Nm3/m3) and in n-C7 conversion (0.1 MPa; 350–370 °C; WHSV, 1 h−1; H2:CH, 10:1 mol/mol). The results have shown that at comparable reaction temperatures, i.e. 340–360 °C the catalysts containing AlSBA-15 are more active than the catalysts supported on SiO2Al2O3. Among the PtMo/AlSBA-15 catalysts, the catalyst containing 8 wt.% of Mo provides the highest selectivity towards i-C16 and the highest iso/n proportion within C10–C15 fraction together with the maintenance of a high conversion. SEM examinations of PtMo catalysts have shown that type of support influences Mo distribution; agglomerates of Mo phases are observed on the AlSBA-15 containing catalysts. It was postulated that the weaker Mo–support interactions and higher acidity in AlSBA-15 supported catalysts resulted in a more active and selective catalyst for hydroconversion of n-hexadecane.

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