Production Of Renewable Hydrocarbons Research Articles

Photocatalyzed hydrodecarboxylation of fatty acids: a prospective method to produce drop-in biofuels.

A direct and practical method for photocatalyzed hydrodecarboxylation of fatty acids is reported herein. The catalytic system consists of a commercially available acridinium salt as the photocatalyst and thiophenol as the Hydrogen Atom Transfer (HAT) co-catalyst. Results evidenced that Cn-1 alkanes were obtained in yields up to 77%. Furthermore, the protocol was employed for a complex mixture of fatty acids bio-derived from a real sample of licuri oil to obtain hydrocarbons in the range of C9-C17 with high selectivity and excellent conversion (>90%). This work provides a powerful strategy for producing drop-in biofuels under mild conditions. Finally, an energetic assessment of our proposed protocol (∼22.9 kW h) reveals the benefit of a sustainable production of renewable hydrocarbons.

Dimer-assisted mechanism of (un)saturated fatty acid decarboxylation for alkene production

The enzymatic decarboxylation of fatty acids (FAs) represents an advance toward the development of biological routes to produce drop-in hydrocarbons. The current mechanism for the P450-catalyzed decarboxylation has been largely established from the bacterial cytochrome P450 OleTJE. Herein, we describe OleTPRN, a poly-unsaturated alkene-producing decarboxylase that outrivals the functional properties of the model enzyme and exploits a distinct molecular mechanism for substrate binding and chemoselectivity. In addition to the high conversion rates into alkenes from a broad range of saturated FAs without dependence on high salt concentrations, OleTPRN can also efficiently produce alkenes from unsaturated (oleic and linoleic) acids, the most abundant FAs found in nature. OleTPRN performs carbon-carbon cleavage by a catalytic itinerary that involves hydrogen-atom transfer by the heme-ferryl intermediate Compound I and features a hydrophobic cradle at the distal region of the substrate-binding pocket, not found in OleTJE, which is proposed to play a role in the productive binding of long-chain FAs and favors the rapid release of products from the metabolism of short-chain FAs. Moreover, it is shown that the dimeric configuration of OleTPRN is involved in the stabilization of the A-A' helical motif, a second-coordination sphere of the substrate, which contributes to the proper accommodation of the aliphatic tail in the distal and medial active-site pocket. These findings provide an alternative molecular mechanism for alkene production by P450 peroxygenases, creating new opportunities for biological production of renewable hydrocarbons.

Renewable Hydrocarbon Production from Waste Cottonseed Oil Pyrolysis and Catalytic Upgrading of Vapors with Mo-Co and Mo-Ni Catalysts Supported on γ-Al2O3.

In this work, the production of renewable hydrocarbons was explored by the means of waste cottonseed oil (WCSO) micropyrolysis at 500 °C. Catalytic upgrading of the pyrolysis vapors was studied using α-Al2O3, γ-Al2O3, Mo-Co/γ-Al2O3, and Mo-Ni/γ-Al2O3 catalysts. The oxygen removal efficiency was much lower in non-catalytic pyrolysis (18.0%), whilst γ-Al2O3 yielded a very high oxygen removal efficiency (91.8%), similar to that obtained with Mo-Co/γ-Al2O3 (92.8%) and higher than that attained with Mo-Ni/γ-Al2O3 (82.0%). Higher conversion yields into total renewable hydrocarbons were obtained with Mo-Co/γ-Al2O3 (61.9 wt.%) in comparison to Mo-Ni/γ-Al2O3 (46.6%). GC/MS analyses showed a relative chemical composition of 31.3, 86.4, and 92.6% of total renewable hydrocarbons and 58.7, 7.2, and 4.2% of oxygenated compounds for non-catalytic bio-oil (BOWCSO), BOMoNi and BOMoCo, respectively. The renewable hydrocarbons that were derived from BOMoNi and BOMoCo were mainly composed by olefins (35.3 and 33.4%), aromatics (31.4 and 28.9%), and paraffins (13.8 and 25.7%). The results revealed the catalysts’ effectiveness in FFA decarbonylation and decarboxylation, as evidenced by significant changes in the van Krevelen space, with the lowest O/C ratio values for BOMoCo and BOMoNi (O/C = 0–0.10) in relation to the BOWCSO (O/C = 0.10–0.20), and by a decrease in the presence of oxygenated compounds in the catalytic bio-oils.

Catalytic pyrolysis (Ni/Al-MCM-41) of palm (Elaeis guineensis) oil to obtain renewable hydrocarbons.

The present work aims to evaluate the potential of Al-MCM-41 and Ni/Al-MCM-41 catalysts for the production of renewable hydrocarbons through the fast pyrolysis of palm oil. Al-MCM-41 mesoporous material was synthesized by the hydrothermal route. The Ni/Al-MCM-41 catalyst was obtained by the wet impregnation method of the Al-MCM-41 material (support) previously synthesized with 2.3% metal in relation to the support mass. The thermal pyrolysis of palm oil yielded many oxygenated compounds with a very high molecular mass. The pyrolysis of the oil under the action of Al-MCM-41 presented greater selectivity when compared to thermal pyrolysis, obtaining 63% of hydrocarbons in the C11–C15 region. The catalytic pyrolysis of the oil with Ni/Al-MCM-41 showed a high deoxygenation rate, obtaining a hydrocarbon percentage equal to 78%, in addition to obtaining a percentage of hydrocarbons equal to 46% in the region of interest, viz., C11–C15, demonstrating the potential of the Ni/Al-MCM-41 catalyst for renewable hydrocarbons production (bio-jet fuel) from palm oil.

Production of renewable hydrocarbons from vegetable oil refining by-product/waste soapstock over selective sulfur-free high metal loading SiO2–Al2O3 supported Ni catalyst via hydrotreatment

The performance, selectivity, recovery, and reusability of high metal loading commercial Ni66 ± 5%/SiO2–Al2O3 catalyst were studied in renewable hydrocarbon synthesis from low cost raw material pretreated soapstock (TS) by solvent-free one-pot hydrotreatment (HT). TS was extracted from rapeseed oil chemical refining by-product/waste soapstock (SS) by developed simple treatment method. The catalyst was characterized by FE-SEM, TEM, XRF, XRD, and N2 sorption analysis. Feedstock, liquid, and gaseous products were analyzed by FT-IR, GC-FID, GC-MS, GC-TCD, and CHNS elemental analysis. The effect of initial H2 pressure (2–8 MPa), catalyst amount (3–9%), reaction temperature (280–340 °C), and residence time (15–60 min) on hydrocarbon production were investigated. Combustible gases and pure marketable linear saturated hydrocarbons with high yield 79.1%, calorific value 47.22 MJ/kg, C/H ratio 5.6, and n-C17 content 82.7% were successfully produced from TS using minimum effective catalyst amount and reaction conditions: 5%, 6 MPa, 320 °C, and 30 min.

Incorporation of Biosolids as Water Replacement in a Two-Step Renewable Hydrocarbon Process: Hydrolysis of Brown Grease with Biosolids

The accumulating volumes of biosolids in lagoons worldwide have intensified the need to develop innovative wastewater treatment strategies. Here, we provide proof-of-concept for the incorporation of biosolids into the hydrolysis step of a two-step thermal conversion of lipids for production of renewable hydrocarbons, which can be utilized as renewable fuels. Brown grease was hydrolysed with biosolids or water at 260–280 °C for 60 min at a mass ratio of 1:1 feed to water or biosolids. The feedstock and products were characterized using various analytical techniques to compare the performance of biosolids to water. The results indicated that there was no significant difference in the degree of hydrolysis of brown grease when biosolids was used as water replacement. The fatty acids composition after hydrolysis when biosolids was used as a water replacement also remained largely unchanged. Hydrolysis of brown grease with biosolids could be achieved at pH ranging from 3.3 to 8.9, and at a lower than previously established temperature. Significantly, the rapid settling of solid material in biosolids observed after thermal hydrolysis of brown grease may reduce the necessity of biosolids settling lagoons. Thus, incorporation of biosolids into a lipid hydrolysis-pyrolysis process may simultaneously benefit the biofuel and waste management sectors.Graphic

Bio-Oil Extracted of Wet Biomass of the Microalga <i>Monoraphidium</i> sp. for Production of Renewable Hydrocarbons

Renewable hydrocarbons refer to fuels consisting of hydrocarbons of 10 to 20 carbon atoms, produced from biomass, and free of oxygen. Hydrocracking, hydrodeoxygenation and hydrotreatment processes for the production of renewable hydrocarbons are described in the literature. Microalgae have been targeted in recent years to synthesize biomass that can be used in the production of biofuels, such as renewable hydrocarbons, biodiesel or ethanol second generation. In this context the lineage Monoraphidium sp. was selected from previous ecophysiological studies and its potential to produce lipids to develop this research related with the extraction of the bio-oil of the wet biomass of Monoraphidium sp. through heat treatment. Consecutively the bio-oil was used as raw material for the production of hydrocarbons through hydrocracking and hydrodeoxygenation processes (HDO) as: decarbonylation, decarboxylation, dehydratation, with in situ production of hydrogen from liquid-phase reforming of glycerol. The reactions were carried out under two different temperature conditions, 350°C and 300°C, respectively, for 1 h and using ruthenium alumina catalyst (Ru/Al2O3). The results showed the bio-oil processing route at a temperature of 350°C promising for the production of hydrocarbons achieving a conversion of 81.54%.

Production of Renewable Hydrocarbons by Thermal Cracking of Oleic Acid in the Presence of Water

The thermal cracking of oleic acid, a model fatty acid, in the temperature range of 390–450 °C was studied in the presence and absence of water. The effect of water on conversion yield and product distribution was determined. Analysis of the pyrolysis product by gas chromatography and mass spectrometry revealed the presence of expected compounds such as alkanes, alkenes, cyclic hydrocarbons, aromatics, and fatty acids in the liquid product. The results showed that distribution of the different classes of compounds was mainly dependent on the reaction temperature. In the absence of water, the products generated from pyrolysis of fatty acids at 430 and 450 °C yielded lower volumes of liquid product and higher amounts of aromatic compounds and solid residues than at 390 °C. However, these reactions still displayed high conversion and low fatty acid content. In the presence of water, an increase in liquid product yield was measured compared to pyrolysis conducted in the absence of water. However, the presence...

Investigation of Carbon Flows in Switzerland with the Special Consideration of Carbon Dioxide as a Feedstock for Sustainable Energy Carriers

AbstractThe substitution of fossil energy carriers by renewable hydrocarbons is a promising measure to reduce net CO2 emissions. The production of renewable hydrocarbons requires hydrogen and carbon. Although hydrogen is easily accessible, the finding of optimal carbon sources requires an understanding of natural and anthropogenic carbon flows. However, there is no overview on the entire carbon flows in Switzerland yet. Although the potential of carbon from biomass is well known, it is unknown whether CO2 is the limiting factor for the production of renewable synthetic fuels. In a comprehensive analysis, 57 carbon paths within Switzerland and across its borders are identified. The carbon flows are quantified for 2013 and illustrated in a Sankey diagram. The diagram is universal and may be applied to other countries in this form. From this analysis, optimal carbon sources for renewable fuels are found. The question is discussed of whether CO2 for synthetic renewable fuels may also originate from nonbiogenic sources. Optimal carbon sources are either biomass or CO2 from incineration plants or cement‐manufacturing plants. If all accessible CO2 from these plants was used for the production of CH4, 43 % of Switzerland's road transportation could be powered with only a very low net CO2 emission if the electric power originates from renewable sources. The limiting factor for the production of synthetic fuel is renewable electrical energy rather than CO2. We propose that the origin of CO2 does not affect the sustainability of the synthetic fuel but the origin of the electric power does.

Bio-oil hydrotreating over conventional CoMo & NiMo catalysts: The role of reaction conditions and additives

Wood-derived bio-oil was investigated as a feedstock for the production of renewable hydrocarbons over commercial hydrotreating CoMoS and NiMoS catalysts. Alumina-supported CoMoS active phase showed better selectivity to diesel-like products than NiMoS phase and higher activity in removal of gaseous intermediates (COx) by hydrogenation. This reaction can play an important role in the reduction of corrosivity at the reactor outlet and determine the process economy. The disadvantage of alumina as a support material was its low stability at high temperatures in presence of water. NiMoS catalyst was found to be more active in decarboxylation and it was possible to reach a steady state production of hydrocarbons having a comparable boiling point distribution with crude oil middle distillates. A test performed with a combination of NiMoS (at the top of the catalyst bed) and CoMoS (at the bottom of the reactor) revealed the key role of the catalyst type and reaction conditions in the first zone of the reactor. The experiments with elevated feeding rates showed the undesirable presence of the not-stabilized reactants behind the first reactor zone. Reaction conditions, catalyst selection and presence of additives (methanol to modify viscosity, DMDS/H2S to stabilize active centers) were combined and optimized to tune the product composition and properties. The catalyst low-temperature activity in the first reactor zone was the limiting factor for the maximum feed rate and reactor capacity. The reaction temperature in this zone strongly affects the boiling point distribution of the product. In case of NiMo catalyst, the reaction temperature above 360°C in the 3rd zone can reduce molecular weight of the product due to mild cracking. In contrast, temperatures above 400°C result in fast deactivation preventing thus the establishment of the steady state operating regime.

Production of Renewable Hydrocarbons from Thermal Conversion of Abietic Acid and Tall Oil Fatty Acids

The primary objective of this study was to investigate the pyrolytic conversion of crude tall oil, a byproduct from the Kraft process in the pulping industry, to hydrocarbon products for use as renewable hydrocarbons and fuels. Abietic acid, the main resin acid in crude tall oil, and tall oil fatty acids, the main distillate fraction of crude tall oil, were pyrolyzed separately using a batch micro reactor at 370, 410, and 450 °C for 2 h. The gas and liquid reaction products were identified and quantified using gas chromatography equipped with a flame ionization detector, a thermal conductivity detector, and mass spectrometry. At all temperature regimes, the pyrolysis of abietic acid resulted in the formation of aromatic compounds characterized by up to three benzene rings. While the pyrolysis of tall oil fatty acids at lower temperatures resulted in alkanes and alkenes and negligible amounts of aromatic compounds, higher temperatures promoted the formation of relatively shorter chain alkanes and alkenes and detectable amounts of aromatics. The presence of both CO and CO2 in the gas fractions suggested that deoxygenation of the initial compounds proceeded through decarbonylation and decarboxylation, but the favored mechanism is dependent upon the structure of the initial substance. This work demonstrates the feasibility of producing renewable hydrocarbons through the pyrolysis of the fatty-acid-rich distillate fraction of crude tall oil.