A.F. Costa

Influence of the external surface area of small crystallite zeolites on the micropore volume determination

Abstract The micropore volumes of zeolites displaying different external surface areas were determined with the help of two classical methods: the Dubinin–Radushkevich (DR) and t-plot. The results were compared with a new approach, in which adsorption isotherms are decomposed into two adsorption areas: one corresponding to the micropore filling and described by the DR equation, and the other ascribed to adsorption on the external surface and ruled by the classical BET equation. The results indicate that the proposed model fits the experimental data very well. Furthermore, the DR-plot seems to overestimate micropore volume, whereas the t-plot, in the range 6

Performance of FCC catalysts prepared with sub-micron Y zeolite

Abstract A sub-micron sample of Y zeolite was synthesized without template with a Si/Al ratio equal to 2.75. This sub-micron zeolite was embedded in a FCC catalyst formulation at two different contents: 10 and 20wt%. The catalysts were hydrothermally deactivated and evaluated in a fixed bed reactor at various catalyst-to-oil ratios and the results compared to the performance of a regular HUSY containing deactivated catalyst. Although the activity of the samples containing sub-micron zeolites in the cracking of gas oil was reduced when compared to a regular HUSY containing catalyst, the selectivity was affected with a reduction in the coke and an increase in both light cycle oil (LCO) yield and the LCO/bottoms ratio. Accordingly to that, those catalysts may be suitable for resid FCC applications.

New supports for co-based fischer-tropsch catalyst

Publisher Summary The gas-to-liquids (GTL) technology is an attractive route to produce high-quality liquid fuels from natural gas; this technology involves the chemical transformation of natural gas that requires three steps: syngas generation, Fischer–Tropsch synthesis (FTS), and product upgrade. The critical step is the FT synthesis that received significant improvements during the past decades both on the reactor and catalyst technologies. Cobalt-based catalysts are typically used at reaction temperatures in the range of 210–250oC, and after the upgrading step (hydrocracking and hydrodewaxing), the main products are premium diesel, food grade paraffin, and specialty lubricants. The desire to enhance the participation of natural gas in the energy matrix gives momentum to the GTL technology, thus motivating the continuous development of new catalysts for the FT synthesis. Reduction promoters, new supports, and support promoters are the focus of various research activities. In this chapter, the effect of ITQ-6 zeolite and mesoporous material SBA-15 as supports for Co-based Fischer–Tropsch catalyst is investigated and compared with a conventional amorphous SiO 2 support.