Production of Middle Distillate Through Hydrocracking of Paraffin Wax over NiMo/SiO2–Al2O3 Catalysts: Effect of SiO2–Al2O3 Composition on Acid Property and Catalytic Performance of NiMo/SiO2–Al2O3 Catalysts

Abstract

SiO 2 -Al 2 O 3 supports with different composition were prepared by a precipitation method in order to control the acid property of SiO 2 -Al 2 O 3 supports. NiMo/ SiO 2 -Al 2 O 3 catalysts were then prepared by an impregnation method and sulfided for use in the production of middle distillate through hydrocracking of paraffin wax. It was revealed that MoS 2 phase was dominantly formed in the NiMo/SiO 2 -Al 2 O 3 catalysts, while Ni-Mo-S phase was not detected due to its fine dispersion. Acidity of NiMo/SiO 2 -Al 2 O 3 catalysts measured by NH 3 -TPD experiments showed a volcano-shaped curve with respect to SiO 2 content. Acidity of the catalysts played an important role in determining the catalytic performance in the hydrocracking of paraffin wax. Conversion of paraffin wax was monotonically increased with increasing acidity of the catalyst, while yield for middle distillate showed a volcano-shaped curve with respect to acidity of the catalyst. Thus, optimal acidity of NiMo/SiO 2 -Al 2 O 3 catalysts was required for the maximum production of middle distillate through hydrocracking of paraffin wax.

Production of middle distillate through hydrocracking of paraffin wax over Pd/SiO2–Al2O3 catalysts

“…The correlation clearly shows that conversion of paraffin wax and selectivity for middle distillate are closely related to the acidity of the catalyst. Conversion of paraffin wax increased with increasing acidity of the catalyst, in good agreement with the previous work [27]. On the other hand, selectivity for middle distillate decreased with increasing acidity of the catalyst.…”

Pd catalyst supported on SiO2–Al2O3 xerogel for hydrocracking of paraffin wax to middle distillate

“…As shown in Fig. 4(a), conversion of paraffin wax increased with increasing acidity of the catalyst, in good agreement with the previous work [40]. It is believed that large acidity of the catalyst enhanced the cracking activity of the catalyst, leading to an increase of conversion of paraffin wax.…”

Preparation of hierarchical β and Y zeolite-containing mesoporous silica–aluminas and their properties for catalytic cracking of n-dodecane

“…These tendencies for Y zeolite-containing catalysts were much larger than those for b zeolite-containing catalysts probably because b zeolite itself has the higher activity for paraffin cracking and the effect of the addition of matrix on the catalytic cracking performance of b zeolite-containing catalysts is lower than that for Y zeolite-containing catalysts. Some reports pointed out that the increase in aluminum content brought about the increase in the catalytic activity [4,34,[36][37][38][39][40][41] and the hydrogen transfer [4,37,41]. It was reported that the diffusion of aluminum into silica skeletal would generate the BrØnsted acid site to increase the activity because the activity increased with increasing calcination temperature of silicaalumina [34].…”