No abstract

Low-carbon light olefins are the basic feedstocks for the petrochemical industry. Catalytic cracking of crude bio-oil and its model compounds (including methanol, ethanol, acetic acid, acetone, and phenol) to light olefins were performed by using the La/HZSM-5 catalyst. The highest olefins yield from crude bio-oil reached 0.19 kg/(kg crude bio-oil). The reaction conditions including temperature, weight hourly space velocity, and addition of La into the HZSM-5 zeolite can be used to control both olefins yield and selectivity. Moderate adjusting the acidity with a suitable ratio between the strong acid and weak acid sites through adding La to the zeolite effectively enhanced the olefins selectivity and improved the catalyst stability. The production of light olefins from crude bio-oil is closely associated with the chemical composition and hydrogen to carbon effective ratios of feedstock. The comparison between the catalytic cracking and pyrolysis of bio-oil was studied. The mechanism of the bio-oil conversion to light olefins was also discussed.

BACKGROUND: Catalytic transformation of bio-oil into higher olefins can provide valuable bio-fuels and chemicals used in the manufacture of high-octane gasoline, detergents, plasticizers and other petrochemicals. This work explores the production of higher olefins from bio-oil through catalytic cracking of bio-oil along with light olefins oligomerization. RESULTS: For bio-oil catalytic cracking, the olefins yield reached 43.8 C-mol% with near-complete bio-oil conversion. The oxygenated organic compounds in bio-oil go through deoxygenation, cracking and hydrogen transfer reactions and form light olefins over the zeolite acid sites. For the oligomerization of light olefins, the highest selectivity and yield of C 5+ olefins over the LTGO catalyst reached 85.4 C-mol% and 326.7 g kg −1 cata h −1 , respectively. Main products below 300 • C were C 6 = -C 12 = olefins, originating from light olefin oligomerization. The influences of the reaction conditions were investigated in detail, and the reaction mechanism was addressed.CONCLUSION: Bio-oil can be catalytically converted to C 2 = -C 4 = light olefins over HZSM-5, and further selectively transformed to C 5 + high olefins via the oligomerization of light olefins over LTGO. The transformation of bio-oil to higher olefins may be useful for the production of bio-fuels and high value chemicals using renewable biomass.