Mild Hydrocracking of Vacuum Gasoil over NiMo-Beta Zeolite Catalysts: The Role of the Location of the NiMo Phases and the Crystallite Size of the Zeolite

Rapid tuning of ZSM-5 crystal size by using polyethylene glycol or colloidal silicalite-1 seed

“…Highly active, selective and stable zeolite catalysts for the reactions of e.g. hydrocracking of alkanes/alkenes, alkylation/hydroxylation of phenol, isomerization of xylene, oligomerization of ethylene, and conversion of methanol-to-hydrocarbons can only be obtained with crystals having suitable size and acidity [5,6,9,12,[14][15][16][17][18][19]. Thus, development of zeolite synthesis methods for finely controlling crystal size is very interesting because it would be possible to considerably improve the catalytic performance [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

“…The crystal size of zeolite has remarkable influence on its catalytic properties due to the significant differences in diffusion length of reactants and products and in number of strong acid sites on external surface sites [1][2][3][4][5][6][7][8]. In the alkylation of toluene with methanol, conventional ZSM-5 crystals (<0.5 lm) shows essentially an equilibrium distribution of xylene product with 23% para-, 23% ortho-and 54% meta-isomers, while an increase in the crystal size to 3 lm led to production of 46% para-xylene as a result of long diffusion path [9].…”

Friedel–Crafts acylation of anisole and toluene with acetic anhydride over nano-sized Beta zeolites

“…Zeolites with a small particle size have exhibited attractive performances in a series of catalytic reactions such as hydrocracking of crude oil, hydroxylation of phenol, isomerization of xylene, and oligomerization of ethylene [12][13][14][15]; the decrease in the crystal size of zeolites can effectively improve their catalytic activity and stability. It is then expected that both activity and stability may be improved by using the zeolites of small crystal size and large external surface as catalysts in the Friedel-Crafts acylation, because the small-sized zeolites can bring on more accessible active sites and the exposed pore openings allow a fast diffusion and desorption of heavy products from the catalysts.…”

Pd catalyst supported on SiO2–Al2O3 xerogel for hydrocracking of paraffin wax to middle distillate

“…It has been reported that metal sites provide hydrogenation-dehydrogenation function, while acid sites provide cracking function through classical and non-classical carbenium ion chemistry [24]. NiMo and NiW catalysts supported on solid acids have been conventionally employed for the production of middle distillate from crude oil [25,26]. In the hydrocracking of FT wax (n-paraffin), however, Pd-loaded catalysts have also been widely used due to their high activity for hydrocracking of sulfur-free hydrocarbons [27].…”