Hydrodeoxygenation of Pinyon-Juniper Catalytic Pyrolysis Oil Using Red Mud-Supported Nickel Catalysts

Red mud (RM) is an alkaline waste generated in the Bayer process of alumina production. In the present study red mud supported nickel catalysts (Ni/RM) were prepared at different concentrations of nickel (10, 20, 30, 40, 50, and 65 wt.%) and used to hydrodeoxygenate (HDO) pinyon-juniper (PJ) catalytic pyrolysis oil. Increasing the nickel content improved the activity of Ni/RM catalysts for HDO reactions. Maximum organic liquid yield (68.6%) was obtained when 40%Ni/RM was used. The upgraded oil had oxygen content of 1.35 wt.% and higher heating value of 45.77 MJ/kg compared to 24.88 wt.% and 28.41 MJ/kg, respectively, for the crude oil. For comparison, commercial Ni/SiO2-Al2O3 was also evaluated in HDO experiments. The HDO oil properties obtained using 40%Ni/RM at reaction temperature of 400 °C was similar to that of commercial Ni/SiO2-Al2O3 at reaction temperature of 450 °C. However, the organic liquid yield was much higher for 40%Ni/RM (68.6%) compared to the commercial Ni/SiO2-Al2O3 (41.8%). The commercial Ni/SiO2-Al2O3 produced more gas (27.6%) than the 40%Ni/RM (16.4%) and the coke yields for the commercial catalyst and Ni/RM catalyst were 7.3% and 4.2% respectively. Overall, application of Ni/RM improved HDO reactions and reduced cracking and coke formation compared to commercial Ni/SiO2-Al2O3

Hydrodeoxygenation of Pinyon Juniper Catalytic Pyrolysis Oil to Hydrocarbon Fuels

As a renewable source, biomass is an essential option for diminishing dependence on conventional fossil fuel energy sources. Pyrolysis is a promising technology for the conversion of biomass into liquid fuels. However, several challenges associated with using pyrolysis oils such as their high acidity and low energy content inhibit their direct use as transportation fuels. We conducted a batch hydrodeoxygenation of pinyon juniper catalytic pyrolysis oil using Ni/SiO2-Al2O3 catalyst to improve the following properties of the oil: heating value, acidity, oxygen content, water content, and viscosity. During the hydrogenation process, the influence of four experimental factors; temperature, catalyst loading, residence time, and hydrogen pressure was investigated. Once hydrogenation was completed, gas, coke, and a liquid product of two immiscible phases (aqueous and organic), were obtained. Maximum hydrogenation was obtained at a reaction temperature of 450 °C with catalyst loading of 20% (wt. % of total bio-oil feedstock), an initial hydrogen cold pressure of 1000 psi and a residence time of 30 minutes. At these conditions, bio-oil was deoxygenated by 96.17%. After hydrodeoxygenation, the higher heating value of the organic liquid product was 45.68 MJ/kg compared to 27.64 MJ/kg of the bio-oil. The water content of the organic liquid was zero compared to 1.63% of the bio-oil using Karl Fischer titration method. The aqueous fraction of the liquid product was 99.61% water. Furthermore, pH of the organic liquid was 6.87 compared to 3.46 of the starting material. The viscosity of bio oil was119.37 cP while it was 1.27 cP for the organic liquid product. The hydrogenation process provided a means of producing upgraded bio-oil, which possessed properties similar to that of gasoline

Hydrodeoxygenation of Acetic Acid As a Model Compound for the Aqueous Phase Catalytic Pyrolysis Oils

Catalytic pyrolysis of biomass generates organic, aqueous, gaseous and solid fractions. The organic fraction can be easily hydrotreated to produce hydrocarbons, but the aqueous phase that contains between 10 to 25% soluble organics can pose challenges in wastewater treatment. The aqueous fraction from the catalytic pyrolysis of Pinyon Juniper wood was characterized for its organic content. The fraction contained about 15 wt% organic compounds determined from Karl Fischer analysis. The organic fractions were further characterized using gas chromatography and mass selective detection (GC/MS). The analysis showed that the dissolved organics were composed of acetic acid, ketones, aldehydes, and phenolic compounds. In this study we investigated the hydrodeoxygenation (HDO) of 15 wt.% acetic acid solution to represent aqueous phase Pinyon Juniper catalytic pyrolysis oil (APPJCPO). HDO experiments were carried out at different temperatures (150, 250, 350, and 450 °C) using Ni/SiO2-Al2O3catalyst in a high pressure Parr reactor. HDO of acetic acid produced acetaldehyde, ethanol, ethyl acetate, carbon dioxide, methane, ethane, and coke at different concentrations depending on the reaction temperature. Reaction pathways of acetic acid HDO were proposed based on analysis of the products. The final products of acetic acid HDO were methane, water at reaction temperature of 450 °C. HDO of APPJCPO was carried out at 450 °C. During HDO the pH of APPJCPO increased from 2.97 to 6.93. The final products of HDO of APPJCPO were water and methane. After HDO experiments, the catalyst was partially deactivated due to coke formation. This study provided insight in the reaction network of acetic acid HDO and suggests that HDO is a promising technique to overcome toxicity and corrosion of aqueous phase pyrolysis oil

Hydrodeoxygenation of Aqueous Phase Catalytic Pyrolysis Oil to Liquid Hydrocarbons Using Multi-Functional Nickel Catalyst

Herein we investigated the hydrodeoxygenation (HDO) of aqueous phase pinyon-juniper catalytic pyrolysis oil (APPJCPO) using a new multifunctional red mud-supported nickel (Ni/RM) catalyst. The organic liquid yield after HDO of APPJCPO using 30 wt. % Ni/RM at reaction temperature of 350 °C was 47.8 wt. % with oxygen content of 1.14 wt. %. The organic liquid fraction consisted of aliphatics, aromatics, and alkylated aromatic hydrocarbons as well as small amounts of oxygenates. The RM support catalyzed ketonization of carboxylic acids. The Ni metal catalyzed partial reduction of oxygenates that underwent carbonyl alkylation with aldehydes and ketones on the RM. Catalyst deactivation assessment suggested that oxidation and coke formation were the main controlling factors for deactivation of Ni and RM respectively. For comparison, commercial (~65wt.%) Ni/SiO2-Al2O3 was tested in HDO experiments which gasified the soluble organics in APPJCPO and did not produce liquid hydrocarbons

Reformulated Red Mud: A Robust Catalyst for In Situ Catalytic Pyrolysis of Biomass

Biomass feedstocks contain inorganic compounds generally classified as ash. The ash consists of compounds of potassium, calcium, magnesium, silicon, phosphorus. and other elements. These elements have been reported to influence both the pyrolysis reactions as well as the destabilization of the pyrolysis oils during storage. The inorganic elements have also been reported to deposit on catalyst surfaces during in situ catalytic pyrolysis leading to the eventual deactivation of acidic catalysts such as zeolites. The deposition of inorganic elements and their effects on formulated red mud (FRM) catalyst during in situ catalytic pyrolysis of pinyon juniper wood was investigated. The inorganic elements were measured for the fresh, coked, and regenerated catalysts. The BET specific surface area of the FRM catalyst decreased from 76 m2/g for the fresh catalyst to 53 m2/g for the stable regenerated catalyst. After three regenerations, the BET specific surface area stabilized at 53 m2/g and remained constant after all other regenerations. Potassium, calcium, magnesium, and phosphorus were deposited on the catalyst. Potassium deposition was linear with the number of regenerations while magnesium and calcium depositions were initially rapid but leveled-off after three regenerations of the catalyst. Phosphorus deposition was almost linear, but the data were more scattered compared to that of potassium. The potassium deposition was attributed to physical phenomenon whereas calcium and magnesium depositions were more akin to chemical reactions related to the loss of BET surface area of the catalyst. The deposition of these elements on the surface of the catalyst did not deactivate it. After each catalyst regeneration, the oil yield was not significantly affected and the oil oxygen content and viscosity decreased slightly. This clearly showed that formulated red mud is a robust catalyst suitable for in situ catalytic fast pyrolysis of biomass

Microvawe pyrolysis of biomass: control of process parameters for high pyrolysis oil yields and enhanced oil quality

The oil yield and quality of pyrolysis oil from microwave heating of biomass was established by studying the behaviour of Larch in microwave processing. This is the first study in biomass pyrolysis to use a microwave processing technique and methodology that is fundamentally scalable, from which the basis of design for a continuous processing system can be derived to maximise oil yield and quality. It is shown systematically that sample size is a vital parameter that has been overlooked by previous work in this field. When sample size is controlled the liquid product yield is comparable to conventional pyrolysis, and can be achieved at an energy input of around 600 kWh/t. The quality of the liquid product is significantly improved compared to conventional pyrolysis processes, which results from the very rapid heating and quenching that can be achieved with microwave processing. The yields of Levoglucosan and phenolic compounds were found to be an order of magnitude higher in microwave pyrolysis when compared with conventional fast pyrolysis. Geometry is a key consideration for the development of a process at scale, and the opportunities and challenges for scale-up are discussed within this paper

Ethanol production of semi-simultaneous saccharification and fermentation from mixture of cotton gin waste and recycled paper sludge

Ethanol production from the steam-exploded mixture of 75% cotton gin waste and 25% recycled paper sludge in various conditions was investigated by semi-simultaneous saccharification and fermentation (SSSF) consisting of a pre-hydrolysis and a simultaneous saccharification and fermentation (SSF). Four cases were studied: 24-h pre-hydrolysis + 48-h SSF (SSSF 24), 12-h pre-hydrolysis + 60-h SSF (SSSF 12), 72-h SSF, and 48-h hydrolysis + 24-h fermentation (SHF). The ethanol concentration, yield, and productivity of SSSF 24 were higher than those of the other operations. A model of SSF was used to simulate the data for four components in SSF. The analysis of the reaction rates of cellobiose, glucose, cell, and ethanol using the model and the parameters from the experiments showed that there was a transition point of the rate-controlling step at which the cell growth control in the initial 2 h was changed to the cellobiose reaction control in later period during ethanol production of SSF from the mixture