ZSM-5, its preparation and use in ethylbenzene dealkylation
AssigneeShell Oil Company
InventorsLászló Domokos, Ralph Haswell, Hong-Xin Li
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Abstract
A new configuration of ZSM-5 is provided whereby the crystals have a higher average silica to alumina ratio at the edges of each crystallite than in the center as determined from a narrow slit line scan profile obtained from SEM/EDX or TEM/EDX elemental analysis. Such ZSM-5 crystals are obtained by a preparation process using L-tartaric acid. The new configuration ZSM-5 provides significantly reduced xylene losses in ethylbenzene dealkylation, especially when combined with silica as binder, and one or more hydrogenation metals selected from platinum, tin, lead, silver, copper, and nickel. Further advantages are found if used in combination with a small crystal size ZSM-5.
Claims10
A process for the preparation of ZSM-5 crystals which comprises:
- synthesizing the crystals from an aqueous reaction mixture comprising an alumina source, a silica source, an alkali source, and L-tartaric acid, or a water-soluble salt thereof.
A process for selecting ZSM-5 crystals having a high selectivity for ethylbenzene dealkylation, which process comprises subjecting the ZSM-5 crystals to SEM/EDX or TEM/EDX elemental analysis;
- calculating the SAR across the crystals;
- and selecting those crystals which exhibit a U-or dish-shaped narrow slit line scan profile on a graph of SAR across the crystallite from edge to edge, wherein the average SAR is higher at the edge of the crystallite than at the centre.
Dependencies are inferred from the claim text.