Techno-economic analysis of an integrated biorefinery to convert poplar into jet fuel, xylitol, and formic acid.

BACKGROUND: The overall goal of the present study is to investigate the economics of an integrated biorefinery converting hybrid poplar into jet fuel, xylitol, and formic acid. The process employs a combination of integrated biological, thermochemical, and electrochemical conversion pathways to convert the carbohydrates in poplar into jet fuel, xylitol, and formic acid production. The C5-sugars are converted into xylitol via hydrogenation. The C6-sugars are converted into jet fuel via fermentation into ethanol, followed by dehydration, oligomerization, and hydrogenation into jet fuel. CO2 produced during fermentation is converted into formic acid via electrolysis, thus, avoiding emissions and improving the process's overall carbon conversion. RESULTS: Three different biorefinery scales are considered: small, intermediate, and large, assuming feedstock supplies of 150, 250, and 760 dry ktonne of poplar/year, respectively. For the intermediate-scale biorefinery, a minimum jet fuel selling price of $3.13/gallon was obtained at a discount rate of 15%. In a favorable scenario where the xylitol price is 25% higher than its current market value, a jet fuel selling price of $0.64/gallon was obtained. Co-locating the biorefinery with a power plant reduces the jet fuel selling price from $3.13 to $1.03 per gallon. CONCLUSION: A unique integrated biorefinery to produce jet fuel was successfully modeled. Analysis of the biorefinery scales shows that the minimum jet fuel selling price for profitability decreases with increasing biorefinery scale, and for all scales, the biorefinery presents favorable economics, leading to a minimum jet fuel selling price lower than the current price for sustainable aviation fuel (SAF). The amount of xylitol and formic produced in a large-scale facility corresponds to 43% and 25%, respectively, of the global market volume of these products. These volumes will saturate the markets, making them infeasible scenarios. In contrast, the small and intermediate-scale biorefineries have product volumes that would not saturate current markets, does not present a feedstock availability problem, and produce jet fuel at a favorable price given the current SAF policy support. It is shown that the price of co-products greatly influences the minimum selling price of jet fuel, and co-location can further reduce the price of jet fuel.

Microwave-assisted catalytic fast pyrolysis of rice husk over a hierarchical HZSM-5/MCM-41 catalyst prepared by organic base alkaline solutions.

This paper reports the results obtained for microwave-assisted catalytic fast pyrolysis (MACFP) of rice husk. The MACFP process employed a hierarchical catalyst prepared via a combination of organic alkali treatment (TPAOH) and the generation of an external layer of MCM-41-type mesoporous channels. We propose this catalyst which is used for the first time for pyrolysis of lignocellulosic biomass, as a tool to reduce coke agglomeration and increase hydrocarbon yields. Our results indicate that during catalyst preparation the mass fraction of cetyltrimethylammonium bromide (CTAB) has a direct effect on the content of MCM-41 formed on top of the HZSM-5 core. For MACFP, we hypothesize that the small molecules generated from thermal decomposition of rice husk react further to form aromatic and aliphatic hydrocarbons by decarbonylation, decarboxylation, oligomerization and aromatization. The highest hydrocarbon yield (60.5%) was obtained for a catalyst modified by a 2.0 mol/L TPAOH solution, with 10 wt% of CTAB (template for producing MCM-41), as well as with digestion and crystallization at 110 °C for 24 h. In addition, the highest liquid yield (47.6 wt%) was obtained at 550 °C. The relative content of hydrocarbons goes through a maximum of 60.5% with CTAB mass fraction which was higher than values obtained with MCM-41 (3.2%) and HZSM-5 (36.0%). Characterization and catalytic testing results suggest that the digestion temperature plays a more important role in the catalyst synthesis than the crystallization temperature. High digestion temperature (120 °C) decreases the overall hydrocarbon selectivity from 60.5% (110 °C) to 39.2%. The relative content of oxygenates reached the lowest value of 35.9% at the digestion and crystallization temperature of 110 °C. The synergistic effect of the MCM-41 shell and the HZSM-5 core promotes the catalytic activity, leading to outstanding deoxygenation capabilities and excellent selectivity to BTEX (52.7%).

Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk using hierarchical micro-mesoporous composite molecular sieve.

Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk over a hierarchical HZSM-5/MCM-41 catalyst was performed in an analytical Py-GC/MS. We evaluated the effect of pyrolysis temperature and the ratio of rice husk to waste greenhouse plastic films on the total peak area of condensable organic products and CO2. In order to evaluate synergy possibilities among the two feedstocks, we performed non-catalytic pyrolysis and catalytic fast pyrolysis of rice husk and waste greenhouse plastic films separately. In addition, we report results for the catalytic fast co-pyrolysis of the mixture rice husk and waste greenhouse plastic films. The maximum relative content of hydrocarbons from catalytic fast co-pyrolysis of rice husk and waste greenhouse plastic films is obtained at 600 °C. When the mass ratio of rice husk to waste greenhouse plastic films is 1:1.5, the relative content of hydrocarbons reaches a maximum (71.1%). The hierarchical micro-mesoporous composite molecular sieve used in this work has outstanding catalytic activity and increases the relative content of hydrocarbons.

Effect of alkali-treated HZSM-5 zeolite on the production of aromatic hydrocarbons from microwave assisted catalytic fast pyrolysis (MACFP) of rice husk.

We performed microwave-assisted catalytic fast pyrolysis (MACFP) of rice husk (RH) over an alkali-treated HZSM-5 zeolite, for production of hydrocarbons. The treatment consisted in the modification of the HZSM-5 by the organic base tetrapropylammonium hydroxide (TPAOH) solution at several concentrations. We characterized the resulting catalysts by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, and temperature-programmed sorption of ammonia (NH3-TPD). The results suggest that the TPAOH treatment generated mesoporous structures in the HZSM-5, while preserving its microporous structure and crystallinity. We obtained the highest yield (45.9%) of hydrocarbons from MACFP of rice husk (RH) at 550 °C. As the TPAOH concentration increases, the relative content of BTEX hydrocarbons (benzene, toluene, ethylbenzene, and xylene) reaches a maximum value of 22.9% at 2.0 mol/L. A comparison of results obtained over the organic base TPAOH (HZSM-5 modified by 2.0 mol/L TPAOH solution) with those obtained over an inorganic base (HZSM-5 modified by 2.0 mol/L NaOH solution) shows a 4.3% increase in the relative content of monocyclic aromatic hydrocarbons for the TPAOH. In addition, the TPAOH-treated catalyst shows excellent selectivity of BTEX (58.5%), which is higher than the selectivity obtained with the parent HZSM-5 (51.2%) and NaOH-treated HZSM-5 (53.9%). The TPAOH-modified HZSM-5 catalyst effectively reduced coke formation by 4.6% compared to MACFP over the parent HZSM-5, most likely because TPAOH decreases the concentration of strong acidic sites on the outer surface of the catalyst, creating a mesoporous structure while retaining the weak acidic sites on the HZSM-5 inner surface. The new catalyst generated in this work contains a moderate amount of mesopores structures, which allows for effective upgrading of pyrolysis vapors while simultaneously reducing coke formation, thereby addressing a significant problem in the development of the catalytic fast pyrolysis process.