Metal‐modified HZSM‐5 catalysts were prepared by the ion exchange of NH4ZSM‐5 (SiO2/Al2O3=23) using Zn, Ga, Ni, and combinations thereof. The prepared catalysts were used to evaluate catalytic pyrolysis for the conversion of Eucalyptus urophylla to fuels and chemicals, specifically aromatic hydrocarbons, by using a micro‐scale pyrolysis reactor coupled with GC–MS. Two different biomass‐to‐catalyst ratios (1:5 and 1:10 w/w) were studied. The catalyst prepared with Ga by total ion exchange (Ga‐HZSM‐5 B, ≈7 wt % Ga) yielded the highest amount of aromatic hydrocarbons, whereas the catalysts modified with Ni produced the lowest yield of aromatic hydrocarbons. A correlation between the methane yield and benzene and p‐xylene selectivity was found for the catalysts, which was observed mainly for the Ni‐, Zn‐, and Ga‐Ni‐modified catalysts. The Ga‐modified catalysts were the most selective for xylenes, whereas the Ni‐based catalysts were the most selective for benzene production with a concurrent increase in methane production. The Zn‐modified catalysts were the most selective for toluene production.
Catalytic fast pyrolysis of eucalyptus wood was performed on a continuous laboratory-scale fluidized bed fast pyrolysis system. Catalytic activity was monitored from use of fresh catalyst up to a cumulative biomass/catalyst ratio (B/C) of 4:1 over extruded pellets of three different ZSM-5 catalysts by tracking CO, CO 2 , H 2 , and C 2 H 4 production and bio-oil quality. The catalysts employed were extruded HZSM-5 with two different silica/alumina ratios (30 and 80) as well as one modified with Ga (SiO 2 /Al 2 O 3 = 30) by ion exchange, which was reduced under H 2 prior to pyrolysis. The deactivation of the catalysts over the course of the experiment was reflected in the decline in deoxygenation activity, following the order HZSM-5 (30) > HZSM-5 (80) > GaZSM-5 (30). HZSM-5 (30) lost most of its activity before a cumulative B/C of 2:1 was reached, while HZSM-5 (80) still showed significant deoxygenated activity at this exposure level. GaZSM-5 (30) still showed deoxygenation activity at B/C of >4:1. The improvement exhibited by HZSM-5 with an increasing SiO 2 /Al 2 O 3 ratio was attributed to reduced acid site density that decreased the propensity for coke formation as a result of reactions occurring between substrates at adjacent active acid sites. For reduced GaZSM-5, initial dehydrogenation activity aided in the production of aromatics by the olefin oligomerization and aromatization route up to B/C of ∼1.5:1, after which Ga became completely oxidized; however, the oxidized GaZSM-5 catalyst continued to exhibit improved decarbonylation and decarboxylation activities.
According to estimates from the International Energy Agency, global energy consumption will increase by at least one third, between 2010 and 2035. The additional power required will be provided not only by fossil sources but also by renewables. While the world energy matrix is supplied only by 13.2% from renewable sources, Brazil has different scenery with renewables accounting for 42.4% of the energy matrix. This work aimed to evaluate the potential use of oleaginous in biorefineries considering the produced quantity, prices, and costs of raw materials and products. Considering the availability of these raw materials, the results showed significant opportunities that can be exploited in Brazil, within the biorefinery concept. Soybean oil is the main raw material for biodiesel production in Brazil, although there are many other vegetable oils with potential for this purpose. Related to the production costs, the soybean biodiesel has higher costs than diesel. Then, this biofuel is only produced due to Brazilian regulatory rules and public subsidies. In order to become this production favorable in the market environment, it is essential to aggregate value to all byproducts and residues generated along the biodiesel production chain. Glycerin is a byproduct of biodiesel that could be used, in a glycerol biorefinery concept, as raw material for the production of value-added products through chemical, biochemical, or thermochemical routes.
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