Conversion of ethanol to propylene over HZSM-5(Ga) co-modified with lanthanum and phosphorous

Conversion of ethanol to propylene was carried out over HZSM-5(Ga) co-modified with lanthanum and phosphorous (La/P/HZSM-5(Ga)). The propylene yield was strongly dependent on both the La/Ga and P/Ga ratios, and the highest value of ca. 29 C-% was obtained at a P/Ga ratio of 1 and a La/Ga ratio of 0.4. FT-IR, 31P MAS NMR, and 71Ga MAS NMR measurements demonstrate that the introduced lanthanum reacts with the pre-introduced phosphorous to regenerate some of Brønsted acid sites (Si(OH)Ga), and accordingly, the Brønsted acid sites are homogeneously distributed within the zeolite framework. In addition, the catalytic stability as well as the catalytic activity of HZSM-5(Ga) was effectively enhanced by co-modification with lanthanum and phosphorous because of the suppression of carbonaceous deposition and elimination of gallium from the zeolite framework.

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► HZSM-5(Ga) co-modified with lanthanum and phosphorous was prepared.
► High propylene yield of ca. 29 C-% was obtained at a P/Ga ratio of 1 and a La/Ga ratio of 0.4.
► Co-modification was very effective for improvement of the catalytic activity and stability of HZSM-5(Ga).