摘要 |
By continuously or intermittently adding amounts of magnetically active moieties, e.g. iron compounds, over time so that the moiety deposits on a catalyst or sorbent in a fluid catalytic cracker or similar circulating hydrocarbon conversion unit, older catalyst, being more magnetic, can be readily separated from catalyst which has been in the system a shorter time. Separation is readily accomplished by passing the catalyst and/or sorbent through a magnetic field and discarding the more magnetic 50% by wt. or more preferably 20% by wt., while recycling the remainder back to the hydrocarbon conversion unit.
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