Untitled

Crude oil to chemicals: light olefins from crude oil

“…In addition, the alkaline earth metal treatment of HZSM-5 zeolite is able to limit hydrogen transfer reactions and stimulate the dehydrogenative cracking by controlling the HZSM-5 acid character and dehydrogenation activity leading to an improve of light olefins yield. 101,107,108 Nevertheless, it has been reported that the thermal and hydrothermal stabilities of the alkali-treated ZSM-5 zeolites are slightly deteriorated because of the introduction of mesopores caused by the desilication. Weak alkali solutions dissolve a small amount of silica and alumina, so create mesopores by enlarging the micropores of zeolites, while strong alkali solutions destroy their crystal structure; therefore, convert them to amorphous materials with macropores and extremely small acid sites.…”

“…114,115 The reported results depict that Co, Cu, Zn, and Ag loaded sites on HZSM-5 zeolites accelerate the dehydrogenation cracking and cyclo-dehydrogenation reactions. 101,107,108 Altogether, the combination of Lewis sites for the dehydrogenation of the paraffinic feedstock with Brönsted acid sites for the cracking of subsequent higher olefins to light olefins, could enhance the yield of light olefins. 116 It has been reported that the iron or chrome incorporation in HZSM-5 leads to increasing the selectivity to aromatic hydrocarbon and decreasing the total olefins, because of improving further oligomerization and cyclization reactions.…”

Effect of process variables on product yield distribution in thermal catalytic cracking of naphtha to light olefins over Fe/HZSM-5

“…The effect of alkaline earth modification on HZSM-5 for catalytic cracking of n-butane was investigated by Wakui et al [12]. The yields of ethylene and propylene over alkaline earth modified HZSM-5 catalysts were high compared with the non-modified HZSM-5.…”

High performance phosphorus-modified ZSM-5 zeolite for butene catalytic cracking

“…Among these zeolites, ZSM-5 zeolite exhibited the most outstanding properties for catalytic cracking because of the unique structure, thermal stability, acidity and shape selectivity [9]. Many elements, such as Fe, Cr, P and rare earth, have been utilized to modify ZSM-5 zeolite for the further enhanced activity [1,[10][11][12]. It has been found that introducing phosphorus increased the attrition resistance of the catalyst particles and also increased the hydrothermal stability of the ZSM-5 zeolite.…”