Metals contamination of aluminosilicate cracking catalysts by Ni- and VO-tetraphenylporphin

• Published in: Journal of catalysis Vol. 108; no. 1; pp. 214 - 232
• Main Authors: Roth, S.A., Iton, L.E., Fleisch, T.H., Meyers, B.L., Marshall, C.L., Delgass, W.N.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 1987; Elsevier
• Subjects: Applied sciences; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units; Scanning electron microscopy; Catalyst poisoning; EPR spectrometry; Vanadium; X ray spectrometry; Fluid catalytic cracking; Zeolite; Silica; Supported catalyst; Metalloporphin; Absorption spectrometry; Adsorption; Nickel; Alumina; Catalyst
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/0021-9517(87)90168-0

The interaction of nickel and vanadyl tetraphenylporphin with amorphous silica-alumina, Y zeolite, and a cracking catalyst containing 15% Y zeolite has been studied with a variety of techniques. For the porphins on the silica-alumina and the cracking catalyst, electronic photoacoustic absorption spectrometry (EPAS), electron paramagnetic resonance (EPR) on V, X-ray photoelectron spectroscopy (XPS), and plasma desorption mass spectrometry (PDMS) confirm interaction of molecularly dispersed porphin molecules with the support but show no demetallation at temperatures below 120 †C. The latter result is supported by EPAS findings of nearly quantitative desorption of the intact metal prophin after redissolution of the impregnated supports. Since the large porphin molecules cannot fit into the intracrystalline pore structure of the zeolite, the effective loading of those samples was several monolayers. Spectroscopic measurements showed, and scanning electron microscopy confirmed that the porphins form crystallites in this case. Blockage of a substantial portion of the external surface of the zeolite particles was indicated, however, by a large reduction in the measured intracrystalline pore volume after porphin impregnation. Infrared spectroscopy showed that porphin decomposition during calcination in air begins at 200–300 °C. On the amorphous silica-alumina-containing materials, the decomposition extends over a 150 °C range during programmed heating. Metal porphins on the zeolite support showed a sharp, apparently catalytic, exotherm and weight loss at a temperature more than 100 °C higher than that for the onset of loss of molecular structure. These results show that interactions of metal porphins with cracking catalysts and their individual components are a strong function of coverage and that the decomposition of the porphins can be influenced by that interaction.