Acidity studies of fluid catalytic cracking catalysts by microcalorimetry and infrared spectroscopy

• Published in: Journal of catalysis 1992-08, Vol.136 (2), p.392-402
• Main Authors: Chen, D., Sharma, S., Cardona-Martínez, N., Dumesic, J.A., Bell, V.A., Hodge, G.D., Madon, R.J.
• Format: Article
• Language: English
• Subjects: 02 PETROLEUM; 020400 - Petroleum- Processing; 400201 - Chemical & Physicochemical Properties; ABSORPTION SPECTROSCOPY; ADSORPTION; ADSORPTION HEAT; ALUMINIUM COMPOUNDS; ALUMINIUM OXIDES; AMORPHOUS STATE; Applied sciences; AZINES; BROENSTED ACIDS; CALORIMETRY; CATALYSTS; CATALYTIC CRACKING; CHALCOGENIDES; CHEMICAL REACTIONS; CRACKING; Crude oil, natural gas and petroleum products; DECOMPOSITION; DISTILLATES; ELECTROMAGNETIC RADIATION; Energy; ENERGY SOURCES; ENTHALPY; Exact sciences and technology; FOSSIL FUELS; FUELS; GAS OILS; HEAT TREATMENTS; HETEROCYCLIC COMPOUNDS; HYDROGEN COMPOUNDS; INFRARED RADIATION; INORGANIC ACIDS; INORGANIC ION EXCHANGERS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ION EXCHANGE MATERIALS; LEWIS ACIDS; MATERIALS; MINERALS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PETROLEUM; PETROLEUM DISTILLATES; PETROLEUM FRACTIONS; PETROLEUM PRODUCTS; PH VALUE; PHYSICAL PROPERTIES; Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units; PYRIDINES; PYROLYSIS; RADIATIONS; SILICATE MINERALS; SILICON COMPOUNDS; SILICON OXIDES; SORPTION; SORPTIVE PROPERTIES; SPECTROSCOPY; STEAM; SURFACE PROPERTIES; THERMOCHEMICAL PROCESSES; THERMODYNAMIC PROPERTIES; ZEOLITES
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/0021-9517(92)90070-X

The acidic properties of a USY-based fluid catalytic cracking catalyst steamed at various severities and amorphous silica-alumina were investigated by microcalorimetry and infrared spectroscopy using pyridine adsorption at 473 K. Microcalorimetric measurements of the differential heat of pyridine adsorption versus adsorbate coverage revealed a heterogeneous acid site distribution for the catalysts. Besides showing the expected progressive decrease in the number of acid sites for pyridine adsorption, our measurements showed that the strength of Bronsted acid sites decreased with increasing severity of steam treatment. Infrared spectra of adsorbed pyridine revealed a significant decrease in the ratio of Brønsted to Lewis acid sites upon steaming. Amorphous silica-alumina had a relatively large number of acid sites of which a large proportion were Brønsted acid sites. However, the strength of these Bronsted sites was lower than that of the mildly steamed USY catalysts. This lower Bronsted acid strength, we believe, is related to lower activity for gas-oil cracking over silica-alumina.