The Thermocatalytic Cracking Process for the Production of Light Olefins and Transportation Fuels from Gas Oils

Abstract

The thermocatalytic cracking (TCC) process, which can selectively produce light olefins (mostly, ethylene and propylene for the petrochemical industry) and transportation fuels (gasoline and diesel fuel), combines the effects of thermal and catalytic cracking reactions. The TCC catalysts consist mainly of mixed metal oxides supported on a high-surface area -thermally stabilized alumina. The best TCC catalyst formulation includes a co-catalyst, which provides the main catalyst component with active hydrogen species formed from hydrogen and other hydrocarbons, particularly methane, produced mainly by thermal cracking. The interparticular interactions of these hydrogen spilt-over species can occur because these species can be easily transferred from one particle to the other through the newly formed pore connections

Catalytic Cracking of Heavy Olefins into Propylene, Ethylene and Other Light Olefins

“…The thermo-catalytic cracking process (TCC) of various liquid hydrocarbon feedstocks (naphthas, gas oils) has been recently developed with the main objective to produce ethylene and propylene, the product propylene/ethylene weight ratio being higher than that obtained by the conventional steam cracking [3][4][5][6]. In addition, the TCC process shows some other important technical and environmental advantages (lower reaction temperatures and less carbon deposition on the reactor walls) [5,6].…”

“…In addition, the TCC process shows some other important technical and environmental advantages (lower reaction temperatures and less carbon deposition on the reactor walls) [5,6].…”

“…The most recent version of the TCC catalysts possesses a hybrid configuration that comprises of a main component and a co-catalyst [5,6]. The role of the main catalyst component is to crack large hydrocarbons of the feed over the cracking sites provided by the (Mo-P) species while the resulting smaller molecules are subsequently cracked onto the (ZSM-5) zeolite acid sites [5].…”

“…The role of the main catalyst component is to crack large hydrocarbons of the feed over the cracking sites provided by the (Mo-P) species while the resulting smaller molecules are subsequently cracked onto the (ZSM-5) zeolite acid sites [5]. The co-catalyst contains a noble metal (Pt or Pd) or Ni being dispersed on a very hydrothermally stable support [5][6][7]. The role assigned to the co-catalyst is to prevent or slow down the currently rapid formation of coke due to the cracking reaction at such relatively high temperatures.…”

“…The role assigned to the co-catalyst is to prevent or slow down the currently rapid formation of coke due to the cracking reaction at such relatively high temperatures. It has been seen that if a rigid and compact network of two ''ideally sparse'' nano-sized particles could be created by using bentonite clay for instance as binding/pressurizing agent, some reaction intermediates would be transferred from one particle to the other, in virtue of the ''pore continuum'' concept [5,6,[8][9][10][11][12][13]. In many reactions (particularly aromatisation, cracking of paraffins and hydrogenation [5][6][7][8][9][10][11][12][13][14][15]), the involved reaction intermediates are ''in situ produced'' hydrogen species.…”