Effect of lanthanum and phosphorus on the aromatization activity of Zn/ZSM-5 in FCC gasoline upgrading

Methanol to aromatics: isolated zinc phosphate groups on HZSM-5 zeolite enhance BTX selectivity and catalytic stability

“…For the ZnHZ catalyst, the zinc content denitely decreased from 0.73% to 0.53% aer rst run. It is also conrmed that the loss of zinc 15,[29][30][31] took place for ZnHZ catalyst, while the ZnPHZ catalyst stabilized the phosphorus and zinc by the form of isolated zinc phosphate groups and further extended the ZnPZ catalyst recycle regeneration times above 20 can be seen in Fig. S10.…”

“…Scanning Transmission Electron Microscopy is used for conrmation of the absence of zinc oxide particles and the catalyst crystallinity of ZnPHZ (JEOL ARM200F, conducted in Hefei, China). NMR measurements were conducted at Sinopec SRIPT for 29 Si, 27 Al and 31 P MAS NMR spectra (Varian VNMR 400). XAFS measurements were performed to identify the chemical states of zinc species.…”

“…Our hypothesis is that the combination of P-modied HZSM-5 catalyst and Zn/ HZSM-5 catalyst could enable both the enhancement of hydrothermal stability and aromatics selectivity of MTA catalysts. Several groups have reported that adding phosphorus to Zn/HZSM-5 promotes the activity and stability of the catalysts in light alkane aromatization by decreasing the loss of zinc, [29][30][31] as well as in aromatization of uid catalytic cracking (FCC) fractions. [31][32][33][34] There are only a handful of ZnPHZ catalyst types used in MTA reaction, 35,36 and most of such reports have been focused on the reaction studies, not the catalyst structure.…”

“…Fig. 1a shown the 29 24,47,48 Based on Loewenstein's rule, 49 the framework Si/Al ratio was calculated and list in Table 1. 50 It suggested that H 3 PO 4 impregnation to HZ sample followed by a subsequent thermal treatment at 550 C led to sort of dealumination of the framework, whereas the addition of zinc species did not affect the zeolite framework.…”

“…29 Si (a),27 Al (b),31 P (c) MAS NMR spectra of catalysts: (1) HZ, (2) PHZ, (3) ZnPHZ, (4) r-Zn 3 (PO 4 ) 2 and (5) PZnHZ. This journal is © The Royal Society of Chemistry 2020 RSC Adv., 2020, 10, 5961-5971 | 5963 Paper RSC Advances Open Access Article.…”