Modification of siliceous zeolites using phosphorus pentachloride

Phosphorus promotion and poisoning in zeolite-based materials: synthesis, characterisation and catalysis

“…Precursors reported with this technique are trimethylphosphite (TMPT), 78,94,95 triphenylphosphine (TPP), 96,97 trimethylphosphine (TMP) 54,59,[90][91][92] and phosphorus pentachloride (PCl 5 ). 98 The zeolite was contacted with the vapour phase of these precursors at elevated temperatures ranging from 360 1C to 600 1C. In the case of TMP a cycle was repeated twice.…”

“…The decrease in the percentage of Si–O–Al bonds is accompanied by a decrease in classic TFAl atoms. 33 , 34 , 37 , 50 , 53 , 55 – 59 , 67 , 69 , 71 , 77 , 78 , 81 , 82 , 84 – 87 , 92 , 98 , 108 – 111…”

“…The decrease in the percentage of Si-O-Al bonds is accompanied by a decrease in classic TFAl atoms. 33,34,37,50,53,[55][56][57][58][59]67,69,71,77,78,81,82,[84][85][86][87]92,98,[108][109][110][111] Due to the decrease in the percentage of Si-O-Al bonds, the crystallinity of zeolites may be reduced to a small extent after the introduction of phosphorus and subsequent thermal treatment, but the framework structure is maintained and no additional crystalline phases have been reported. 30,53,58,63,64,71,73,76,77,[81][82][83][84]101,110 A loss of crystallinity was found for samples treated with acidic and non-acidic precursors and with the use of impregnation solutions of different acidities, excluding acid leaching as the source of the loss of crystallinity.…”

Acid properties and catalysis of USY zeolite with different extra-framework aluminum concentration

“…The USY zeolite has been modified by hydrothermal treatment, which can result in the dealumination of the skeleton with total content of Al, Si and Na remaining unchanged [16]. However, it's dealuminum degree is rather limited and the non-framework aluminum formed during the steam treatment may affect the catalytic performance.…”

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

“…53 For PHZ sample, the band at À8 ppm could be observed due to the association of the octahedral Al sites with phosphorus (Al oct-o-p ). 22,47,54 The broad band appeared at the range of 45 to 15 ppm in comparison to the HZ sample. It suggested the increase of Al tet-dis and A ltet-nf sites, which was correlated with the bonding of Al with phosphorus species.…”