An efficient catalyst is desired to produce lighter isoparaffins from heavy
n-paraffins by isomerization and hydrocracking, which are environmentally friendly processes for producing high-octane fuel. This paper assesses the suitability of a catalyst consisting of beta zeolite and nanosized (
i.e., 5-50 nm; hereafter
ns) alumina particles for isomerization and hydrocracking of large
n-paraffins. The catalytic performances of three catalysts, namely an alumina-supported metal catalyst (NiMo/
γ-Al
2O
3), a two-component catalyst (
ns Al
2O
3–beta zeolite), and a three-component catalyst (NiMo/
γ-Al
2O
3–
ns Al
2O
3–beta zeolite) for an isothermal reaction with
n-hexadecane were evaluated. The results reveal that the conversion and selectivity are improved by increasing the number of components in a catalyst. Specifically, the three-component catalyst exhibits superior catalytic performance between 225 and 350 °C due to concerted effect of the three components. We investigated the effect of the SiO
2/Al
2O
3 molar ratio of beta zeolite on the performance of three-component catalysts and found that beta zeolite with a SiO
2/Al
2O
3 molar ratio of 25 has a higher activity and cracking selectivity with high isoparaffin selectivity of the cracked products (hereafter
iso-selectivity) than three-component catalysts with SiO
2/Al
2O
3 molar ratios of 16, 50, and 150; this indicates that there is an optimum SiO
2/Al
2O
3 molar ratio of zeolite in the three-component catalyst.The three-component catalyst composed of NiMo/
γ-Al
2O
3,
ns Al
2O
3, and dealuminated beta zeolite had a high conversion and
iso-selectivity. Its catalytic performance is more suitable for producing isoparaffins of gasoline fraction than these of three three-component catalysts composed of
ns Al
2O
3 and non-dealuminated beta zeolite,
ns SiO
2 and non-dealuminated beta zeolite, or
ns SiO
2 and dealuminated beta zeolite. Acid treating was found to remove extra-framework aluminum and amorphous alumina from the beta zeolite surface to make Si–OH. It produced reformed acid sites between the Si–OH of the external zeolite surface and
ns Al
2O
3 surfaces, which consequently improved the isomerization and cracking activities due to the acid sites existing at nanopores.
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