On-stream stability enhancement of HZSM-5 based fluid catalytic cracking naphtha hydro-upgrading catalyst via magnesium modification

• Increasing MgO loading leads to the increased ratio of Lewis acid sites to Brönsted ones.
• The suitable ratio of medium and strong Lewis acid sites to medium and strong Brönsted ones is about 1.
• The suitable optimum ratio of total Lewis acid sites to total Brönsted ones is 2–3.
• Formation of coke with lower H/C ratio is the main factor accounting for catalyst deactivation.

On-stream stability of fluid catalytic cracking (FCC) naphtha hydro-upgrading catalysts that convert olefins into high-octane isoparaffins and aromatics is crucial for guaranteeing the long-term operation of industrial units, and therefore suppressing catalyst deactivation due to coking becomes the focus of FCC naphtha hydro-upgrading process and catalyst development. Here we report a simple and novel strategy to enhance the on-stream stability of a HZSM-5 based FCC naphtha hydro-upgrading catalyst by magnesium modification. The characterization and catalytic test results showed that the incorporation of a suitable amount of MgO can adjust the ratio of Lewis acid sites to Brönsted ones and thereby significantly improve stability of the resulting catalyst.

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