Synergetic and Antagonistic Effects in Hydroconversion Catalysts Composed of Mixtures of Solid Acids

Hydroisomerization and hydrocracking using bifunctional catalysts with hydrogenation-dehydrogenation next to the Brønsted acid functionality are key refinery processes converting heavy petroleum fractions as well as renewable hydrocarbons to high grade lubricants and fuels. Bifunctional catalysts are composed of an acid porous material and a trace amount of noble metal. In the field of long-chain n-paraffins hydroconversion, maximizing the yield of skeletal isomers from n-alkanes is an important challenge. In this field, catalyst design involving combination of different acidic solid phases is a new strategy. The implementation of diversity in terms of catalytic performances in one and the same catalyst is expected to favor the occurrence of synergetic effects. Experimentally, the evaluation of combinations of different solids in different proportions leads to a significant number of formulations to be tested. In this work, high-throughput experimentation (HTE) tools for catalytic evaluation were implemented, accelerating the catalytic evaluation and the discovery of mixtures of interest. An initial set of twenty-one acid solids comprising zeolites including IZM-2, an IFPEn proprietary zeolite with unknown crystallographic structure, silicoaluminophosphates, mesoporous and mesostructured silica-alumina was selected. For evaluating the catalysts the hydroconversion of n-hexadecane in vapor phase was selected. A SPIDER HTE catalytic testing unit with 16 parallel catalyst beds was developed and validated. First the Pt loading was optimized for each solid of the library in order to obtain well-balanced bifunctional catalytic behavior. The desired catalytic diversity was evaluated according to seven catalytic descriptors of the twenty-one well-balanced candidate bifunctional catalysts. A sufficient dispersion of the candidates in the space of the seven descriptors was obtained. Among the evaluated bifunctional catalysts, Pt/IZM-2 appeared as an excellent hydroisomerization catalyst especially suited for formation of multibranched skeletal isomers. The new IZM-2 zeolite with unknown structure was found to be a valuable addition to the family of shape selective zeolites. In catalytic test reactions for probing pore architecture IZM-2 showed properties typical of 10-membered ring as well as 12-membered ring zeolites. In this instance, the advantageous combination of catalytic properties targeted in this project was present in one single acid solid. The excellent performance of IZM-2 in hexadecane hydroisomerization may find application in dewaxing through selective hydroisomerization of long chain n-alkanes.Based on the initial set of solids, the total number of possible binary combinations was still too large for experimental evaluation even when using the HTE tool. Based on the determined diversity a more limited number of catalysts were selected for a 10-elements catalyst library. The selection maximized diversity in terms of catalytic properties in the space of the seven catalytic descriptors. Mixtures were selected based on diversity criteria. With three of the thirty evaluated binary mixtures, synergetic effects were observed.status: publishe