Hydrothermal Catalytic Cracking of Fatty Acids with HZSM-5

Abstract

We explored the hydrothermal cracking of palmitic acid by HZSM-5 zeolite in a batch reactor. The major liquid products were aromatic hydrocarbons (e.g., xylenes, toluene) and alkanes (e.g., 2-methyl-pentane, heptane). The major gaseous products were CO and CO2, but appreciable yields of propane and butane were also obtained. The effects of batch holding time, temperature, hydrogen pressure, and water density on product yields were elucidated. Total yields of gas and liquid products exceeding 90 wt % are available at reaction conditions of 400 °C, 180 min, and either with no added H2 and a water density of 0.1 g/mL or less or with added H2 and a water density of 0.15 g/mL. The activation energy for palmitic acid disappearance is 31 ± 1 kJ/mol. The zeolite catalyst undergoes some modest structural changes under the hydrothermal reaction conditions employed, but the catalyst can be regenerated by controlled oxidation to remove coke and calcination to restore the structure. These results demonstrate the technical feasibility of using HZSM-5 under hydrothermal conditions to produce valuable chemicals from renewable fatty acid feedstocks.

Development of nickel based catalysts for the transformation of natural triglycerides and related compounds into green diesel: a critical review

“…The cracking/hydrocracking ( Fig. 2) performed over acidic catalysts results to the so-called organic liquid product, namely a mixture of hydrocarbons (in the gasoline, kerosene and diesel range) with traces of shorter chain oxygenates as well as hydrocarbon gases (C 3 -C 5 ) and coke [74 and references there in, [84][85][86][87][88][89][90][91]. The hydrocarbons obtained by cracking of triglycerides consist, besides paraffins, of naphthenes and aromatics obtained by secondary reactions.…”

Functional carbons and carbon nanohybrids for the catalytic conversion of biomass to renewable chemicals in the condensed phase

“…More interestingly, the carbonaceous deposits formed under reaction conditions appeared to protect Pt/γ-Al2O3 and ZSM-5, the latter being stable even at a very high temperature (400 °C) [22]. It appears that carbon is a promising candidate to passivate the surface and improve the stability of a large variety of oxides [22,29].…”

“…2). Currently, ZSM-5 seems to be the only zeolite stable under hydrothermal conditions [8,22]. Figure 2.…”

Catalytic hydrothermal processing of lipids using metal doped zeolites

“…ZSM-5 also possesses a high concentration of Lewis acid and Brønsted acid sites. HZSM-5 enhances the hydrothermal catalytic cracking of palmitic acid at 400 °C resulting in the production of a large range of hydrocarbons [18]. In a more recent study, HZSM-5 with a low Si/Al ratio of 23 was more selective for producing BTX aromatics (benzene, toluene and xylene) from palmitic acid at 400 °C compared to higher Si/Al ratio.…”