Hydrothermal Decarboxylation Research Articles

The Effect of Activated Carbon Pellet on Hydrothermal Decarboxylation of Palm Olein into Renewable Diesel

The Effect of Activated Carbon Pellet on Hydrothermal Decarboxylation of Palm Olein into Renewable Diesel

Catalytic Decarboxylation of Palm Oil to Green Diesel over Pellets of Ni-CaO/Activated Carbon (AC) Catalyst Under Subcritical Water

There has been a considerable in converting palm oil to green diesel. Green diesel is a hydrocarbon compound similar to conventional diesel fuel's components. It is expected to substitute conventional diesel fuel in diesel vehicle engines. The process of producing diesel is also called the deoxygenation process. One of the deoxygenation processes is decarboxylation. The current study evaluates the performance of Ni-CaO/AC catalyst in the form of pellets by mixing a powder Ni-CaO/AC catalyst and phenolic resin. The aim of this study namely to evaluate the performance pellets of Ni-CaO/AC catalyst in the decarboxylation of palm oil under sub-critical water. This research includes catalyst activity carried out by decarboxylation in subcritical water with temperature variations: 300, 310, 320, and 330 °C using pellets of Ni-CaO/AC catalyst. The decarboxylation products obtained were analyzed with Gas Chromatography-Mass Spectroscopy (GC-MS). The results obtained in this study showed that the highest percentage composition and selectivity of green diesel were obtained at a temperature of 330 °C, with values of 18.08 and 22.07, respectively. These results suggest that higher temperature promotes the hydrogenation-decarboxylation reaction of palm oil. Pellets of Ni-CaO/AC catalyst can increase the selectivity of green diesel if the phenolic resin is replaced with a binder that can provide physical strength to the catalyst but does not damage the function and cover much of the active surface area of the catalyst. We can conclude that pellets of Ni-CaO/AC catalysts have the potential to do hydrothermal decarboxylation if the increased operating condition.

NiCo/SiO2 nanospheres for efficient synergetic decarboxylation of fatty acids and upgrading of municipal sludge HTL bio-crude to biofuels

Municipal sludge (MS) and derived HTL (hydrothermal liquefaction) bio-crude contains a large quantity of organics, including fatty acids, which may be a potential resource for producing biofuels via catalytic treatment. Herein, decarboxylation of fatty acids is chosen as the model reaction to screen a series of nickel-based bimetallic catalysts supported on homemade SiO2 nanospheres to investigate the synergetic effect. NiCo/SiO2 turned out with the best performance compared to NiCu-, NiZn-, NiMo- and NiFe/SiO2. An 83% conversion of stearic acid and an 84% selectivity of heptadecane via hydrothermal decarboxylation were achieved at 280 °C under 1 MPa H2. XPS results revealed the electron transfer from Co to Ni, leading to the formation of Niδ-, which is more accessible to bond with Cδ+ in the carboxyl group of fatty acids, thus facilitating the decarboxylation reaction. Compared to commercial SiO2, our homemade SiO2 showed a stronger carbon accumulation resistance, indicating a medium specific surface area was essential. Both the synergetic effect of NiCo bimetal and the carbon accumulation resistance of homemade SiO2 nanospheres contributed to the efficient hydrothermal decarboxylation. The NiCo/SiO2 catalyst was further applied for upgrading of MS HTL bio-crude to biofuels, and the theoretical higher heating value (HHV) was significantly improved from 34.4 to 37.2 MJ/kg, suggesting the potential application of converting MS bio-crude to biofuels.

An asymmetric mononuclear cobalt(II) compound derived from 3-bromo-pyridine-2,6-dicarboxylic acid involving in-situ hydrothermal decarboxylation: structure, magnetic property and Hirshfeld surface analysis

Abstract A new cobalt(II) compound with the formula [Co(5-Br-pyc)(2,2′-bipy)(H2O)(Cl)]·2H2O (1·H2O) (5-Br-Hpyc = 5-bromo-pyridine-2-carboxylic acid, 2,2′-bipy = 2,2′-bipyridine) has been hydrothermally synthesized and well characterized. The X-ray single-crystal diffraction analysis showed that 1⋅2H2O has crystallizes in the monoclinic system, space group P21/c (no. 14). The Co(II) center was octahedrally bonded by one bidentate chelate 5-Br-pyc anion and one 2,2′-bipy, one water molecule as well as one chloride anion to form the mononuclear structure of 1⋅2H2O. Complex 1⋅2H2O forms a 3D network through abundant O–H⋅⋅⋅O hydrogen bonds and π⋅⋅⋅π stacking interactions. Notably, the 5-Br-Hpyc ligand was in situ generated by decarboxylation of the 3-bromo-pyridine-2,6-dicarboxylic acid (3-Br-H2pydc) precursor selectively on 2-position under hydrothermal conditions. The magnetic properties, the Hirshfeld surface structure and the synthetic process for 1⋅2H2O have been carefully described and discussed.

Optimisation of Propane Production from Hydrothermal Decarboxylation of Butyric Acid Using Pt/C Catalyst: Influence of Gaseous Reaction Atmospheres

The displacement and eventual replacement of fossil-derived fuel gases with biomass-derived alternatives can help the energy sector to achieve net zero by 2050. Decarboxylation of butyric acid, which can be obtained from biomass, can produce high yields of propane, a component of liquefied petroleum gases. The use of different gaseous reaction atmospheres of nitrogen, hydrogen, and compressed air during the catalytic hydrothermal conversion of butyric acid to propane have been investigated in a batch reactor within a temperature range of 200–350 °C. The experimental results were statistically evaluated to find the optimum conditions to produce propane via decarboxylation while minimizing other potential side reactions. The results revealed that nitrogen gas was the most appropriate atmosphere to control propane production under the test conditions between 250 °C and 300 °C, during which the highest hydrocarbon selectivity for propane of up to 97% was achieved. Below this temperature range, butyric acid conversion remained low under the three reaction atmospheres. Above 300 °C, competing reactions became more significant. Under compressed air atmosphere, oxidation to CO2 became dominant, and under nitrogen, thermal cracking of propane became significant, producing both ethane and methane as side products. Interestingly, under a hydrogen atmosphere, hydrogenolytic cracking propane became dominant, leading to multiple C–C bond cleavages to produce methane as the main side product at 350 °C.

Process modelling and economic evaluation of biopropane production from aqueous butyric acid feedstock

Catalytic hydrothermal decarboxylation of biomass-derived butyric acid can produce renewable biopropane as a direct drop-in replacement fuel for liquefied petroleum gases. In this present study, experimental results from a batch reactor have been used to develop a hypothetical continuous process to deliver 20,000 tonnes/year of biopropane, as base-case capacity, from 10 wt% aqueous butyric acid. A combination of process synthesis and ASPEN Hysys simulation have been used to formulate a process flowsheet, after equipment selection. The flowsheet has been used to carry out economic analyses, which show that the minimum selling price of biopropane is $2.51/kg without selling the CO2 co-product. However, with the incorporation of existing UK renewable energy incentives, the minimum selling price can reduce to $0.98/kg, which is cheaper than the current $1.25/kg selling price for fossil liquefied petroleum gases. Sensitivity analysis based on raw material costs and production capacities show profound influence on the minimum selling price, with strong potentials to making biopropane competitive without incentivisation, whereas the influence of selling CO2 is marginal. While this biopropane technology appears promising, it still requires more detailed technical and process data, life-cycle analysis and detail economic costings and testing at a pilot-scale prior to commercial exploitation.

Parametric Study of Pt/C-Catalysed Hydrothermal Decarboxylation of Butyric Acid as a Potential Route for Biopropane Production

Sustainable fuel-range hydrocarbons can be produced via the catalytic decarboxylation of biomass-derived carboxylic acids without the need for hydrogen addition. In this present study, 5 wt% platinum on carbon (Pt/C) has been found to be an effective catalyst for hydrothermally decarboxylating butyric acid in order to produce mainly propane and carbon dioxide. However, optimisation of the reaction conditions is required to minimise secondary reactions and increase hydrocarbon selectivity towards propane. To do this, reactions using the catalyst with varying parameters such as reaction temperatures, residence times, feedstock loading and bulk catalyst loading were carried out in a batch reactor. The highest yield of propane obtained was 47 wt% (close to the theoretical decarboxylation yield of 50 wt% on butyric acid basis), corresponding to a 96% hydrocarbon selectivity towards propane. The results showed that the optimum parameters to produce the highest yield of propane, from the range investigated, were 0.5 g butyric acid (0.57 M aqueous solution), 1.0 g Pt/C (50 mg Pt content) at 300 °C for 1 h. The reusability of the catalyst was also investigated, which showed little or no loss of catalytic activity after four cycles. This work has shown that Pt/C is a suitable and potentially hydrothermally stable heterogeneous catalyst for making biopropane, a major component of bioLPG, from aqueous butyric acid solutions, which can be sourced from bio-derived feedstocks via acetone-butanol-ethanol (ABE) fermentation.

The syntheses, structures, and magnetic properties of two mononuclear manganese(II) complexes involving in situ hydrothermal decarboxylation

Abstract Two new mononuclear compounds [Mn(3-Br-pydc)(H2O)3] (1) and {[Mn(5-Br-pyc)(bipy)(H2O)(Cl)]·2H2O (2) (3-Br-H2pydc = 3-Br-pyridine-2,6-dicarboxylic acid, 5-Br-Hpyc = 5-Br-pyridine-2-carboxylic acid, bipy = 2,2′-bipyridine) have been synthesized by traditional solution reaction and hydrothermal reaction, respectively. In both compounds, the MnII center is six-coordinated in a distorted octahedral geometry, formed by one tridentate chelate 3-Br-pydc dianion and three water molecules in 1, while the coordination sphere consists of one bidentate chelate 5-Br-pyc anion, one bipy, one water molecule, and one chloride anion in 2 (MnNO5 for 1 and MnN3O2Cl for 2). O–H⋯O hydrogen bonds, Br⋯O halogen bonds, and/or π-π stacking assist in the construction of the three-dimensional (3D) network structures of 1 and 2. Notably, the 5-Br-Hpyc ligand was generated in situ by decarboxylation of the 3-Br-H2pydc precursor under hydrothermal conditions. Variable-temperature magnetic susceptibility data in the 2–300 K temperature range indicate weak antiferromagnetic coupling in both 1 and 2.

Synthesis, Structure and Fluorescent Property of a Novel 3D Rod‐Packing Microporous Zn(II) MOF Based on a Temperature‐Induced In Situ Ligand Reaction

AbstractThe self‐assembly process of 2,2′‐bipyridine‐4,4′,6,6′‐tetracarboxylic acid (H4bptc) and Zn(II) centers has been implemented under hydrothermal condition, while surprisingly, due to the high reaction temperature, the H4bptc ligand transformed into 2,2′‐bipyridine‐4,6,6′‐tricarboxylic (H3bptc′) with an unexpected in situ ligand reaction (hydrothermal decarboxylation) during the synthetic process. And finally, a novel Zn(II) MOF {[Zn1.5(bptc′)(H2O)]⋅H2O}n (1) has been obtained, which is characterized by single‐crystal X‐ray diffraction, powder X‐ray diffraction (PXRD), thermogravimetric analyse (TGA), elemental analyse (EA) and infrared spectroscopy (IR). In MOF 1, the 1D [Zn1‐O6,6′‐carboxyl‐Zn2]n double chains are connected by the 4‐carboxyl of R‐ or S‐bptc′ ligands into a 3D double‐walled rod‐packing framework with three kinds of windows. In addition, the solid‐state fluorescent property of 1 was conducted at room temperature, and meanwhile, 1 showed high selectivity and sensitivity for MnO4− ion by fluorescent quenching effect.

Catalytic Hydrothermal Decarboxylation and Cracking of Fatty Acids and Lipids over Ru/C

Here, we report on the catalytic hydrothermal conversion of fatty acids and lipids to a range of hydrocarbons using Ru/C without the need for addition of external H2 supplies. Catalyst screening ex...

Catalytic hydrothermal deoxygenation of fatty acids over palladium on activated carbon catalyst (Pd/C) for renewable diesel production

Renewable diesel, a potential substitute for petroleum diesel, is usually produced from biological sources by deoxygenating fatty acids in the presence of organic solvents with the addition of hydrogen. This could pose a health challenge and increase the cost of production. The current work was conducted in subcritical water without the addition of hydrogen using palmitic and oleic acids as fatty acids. The impact of temperature and reaction time was assessed using 5% palladium on activated carbon (Pd/C) catalyst. The recovered organic products were analysed for hydrocarbons using gas chromatography. The results show that the main hydrocarbon products from palmitic and oleic acids were pentadecane and heptadecane, respectively. The maximum value of the molar yield of pentadecane was 35.4% at the optimum conditions of 290 °C and 1.5 h, and that from heptadecane was 16.6% at 330 °C and 4 h. This shows that 5% Pd/C is active for catalysing the hydrothermal decarboxylation of the fatty acids to hydrocarbons. With these results, the cost of production can probably be reduced and the capacity to use hydrocarbons from a renewable resource to displace conventional diesel can be increased.

Catalytic hydrothermal deoxygenation of the lipid fraction of activated sludge

The need for sustainable wastewater treatment and search for cheap feedstock for renewable energy production have driven investigators to evaluate the potential of producing biofuels from waste materials such as sewage sludge. The current work is aimed at assessing the potential for producing hydrocarbons from the lipid fraction of activated sludge via a catalytic hydrothermal decarboxylation reaction under varying residence time. Impacts of platinum on carbon (Pt/C) and palladium on carbon (Pd/C) catalysts were evaluated at 290 °C and residence time of 0.5, 1, 3 and 4 h. The analyses of the lipids and hydrocarbons were done using high-temperature gas chromatography. The results show that at the optimum conditions of 1 h, 290 °C, 20 mg of catalyst, 100 mg of lipid extract and 15 mL of water, the maximum yield of hydrocarbon was 23.2% of pentadecane obtained using Pt/C. This shows that the dominant hydrocarbon is pentadecane and that Pt/C exhibited greater catalytic effect than did Pd/C. The hydrocarbons might be used directly as renewable diesel and as such will contribute to the mitigation of climate change since emission of greenhouse gases will be reduced, and the use of activated sludge as the feedstock is expected to help minimize the cost of production and to ensure sustainable wastewater treatment.

Renewable diesel production by hydrothermal decarboxylation of fatty acids over platinum on carbon catalyst

For over a decade researchers have been investigating the potential to produce renewable diesel from fatty acid, possibly because it possesses good qualities such as very high cetane number, oxidative stability, and renewability, and can be produced and transported using existing refinery process facilities, making it a potential substitute for petroleum diesel. Most of these investigations required the use of organic solvents and hydrogen which might increase the cost of production. To avoid this, the current work was conducted in an aqueous medium without the addition of hydrogen, using hydrothermal decarboxylation of palmitic and oleic acids in the presence of 5% platinum on carbon catalyst. The performance of the primary products pentadecane and heptadecane obtained was optimized by determining the optimum operating conditions of temperature and residence time. The results showed that the highest molar yield of pentadecane from palmitic acid was 55.3% at the optimum conditions of 290 °C and 1.5 h, and that of heptadecane from oleic acid was 16.4% at 290 °C and 4 h. With these results the cost of production might be reduced and using a benign, environmentally friendly medium would help to reduce the risk associated with the use of organic solvents.

Solid and solution states studies of two Mn(II) complexes based on N-oxidized pyridine-2,5-dicarboxylic acid

Two coordination complexes, [Mn2(pydco)2(phen)2(H2O)2]·2H2O (1) and [Mn(3-pyco)2(H2O)4] (2), based on Mn(II), pyridine-2,5-dicarboxylic acid N-oxide (H2pydco), and 1,10-phenanthroline (phen) as organic ligands have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single crystal X-ray diffraction. We have synthesized the first Mn(II) complex of H2pydco. Interestingly, in situ hydrothermal decarboxylation occurred in 2 and (pydco)2– was totally transformed into pyridine-3-carboxylate N-oxide (3-pyco)– under hydrothermal conditions. The complexation reactions of these molecules with Mn2+ ions were investigated by means of solution studies. The stoichiometry of the most abundant species in the solution (prior to the pH at which precipitation occurs) was very close to that of the corresponding crystalline solid-state complexes.

Continuous Hydrothermal Decarboxylation of Fatty Acids and Their Derivatives into Liquid Hydrocarbons Using Mo/Al2O3 Catalyst.

In this study, we report a single-step continuous production of straight-chain liquid hydrocarbons from oleic acid and other fatty acid derivatives of interest including castor oil, frying oil, and palm oil using Mo, MgO, and Ni on Al2O3 as catalysts in subcritical water. Straight-chain hydrocarbons were obtained via decarboxylation and hydrogenation reactions with no added hydrogen. Mo/Al2O3 catalyst was found to exhibit a higher degree of decarboxylation (92%) and liquid yield (71%) compared to the other two examined catalysts (MgO/Al2O3, Ni/Al2O3) at the maximized conditions of 375 °C, 4 h of space time, and a volume ratio of 5:1 of water to oleic acid. The obtained liquid product has a similar density (0.85 kg/m3 at 15.6 °C) and high heating value (44.7 MJ/kg) as commercial fuels including kerosene (0.78–0.82 kg/m3 and 46.2 MJ/kg), jet fuel (0.78–0.84 kg/m3 and 43.5 MJ/kg), and diesel fuel (0.80–0.96 kg/m3 and 44.8 MJ/kg). The reaction conditions including temperature, volume ratio of water-to-feed, and space time were maximized for the Mo/Al2O3 catalyst. Characterization of the spent catalysts showed that a significant amount of amorphous carbon deposited on the catalyst could be removed by simple carbon burning in air with the catalyst recycled and reused.

A novel process for the production of aromatic hydrocarbons from brown coal in water medium by hydrothermal oxidation and catalytic hydrothermal decarboxylation

With no use of hydrogen or a hydrogen donor, a novel process is proposed for the production of aromatic hydrocarbons from brown coal in water medium, which consists of hydrothermal oxidation at 240°C and Cu2O-catalysed hydrothermal decarboxylation at 350°C. Using this hydrothermal oxidation and catalytic hydrothermal decarboxylation method, aromatic carboxylic acids were formed from brown coal by an oxidation process, and then decarboxylated to the corresponding aromatic hydrocarbons. The validity of the decarboxylation method was examined using several aromatic carboxylic acids as model compounds for the acid products after hydrothermal oxidation of brown coal, including o-phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesic acid, 1-naphthoic acid, 2-naphthoic acid, and 2,6-naphthalic acid. Use of Cu2O catalyst increased the decarboxylation yields of all the aromatic carboxylic acids. Especially for benzene carboxylic acids, all decarboxylation yields were above 90% with 100% selectivity. The Cu2O-catalysed hydrothermal method was proven to be effective, not only for the decarboxylation reactions from monocarboxylic acids to hydrocarbons, but also for the decarboxylation reactions from tricarboxylic acids to dicarboxylic acids and from dicarboxylic acids to monocarboxylic acids. In the presence of alkali and oxygen during the oxidation process, various valuable aromatic hydrocarbons and heterocyclic compounds, especially benzene, were obtained from Loy Yang coal using the hydrothermal oxidation and catalytic decarboxylation process. Based on analyses of aromatic carboxylic acids or ions before and after the decarboxylation process, it was found that decarboxylation reactions were the major reactions and the use of Cu2O was effective not only for the decarboxylation from monocarboxylic acids but also from polycarboxylic acids to monocarboxylic acids, consistent with the results for the model aromatic carboxylic acids. Additionally, it was found that a Cu2O catalyst was also effective for the conversion of ‘heavy’ compounds in oxidised coal to ‘light’ compounds.

Biofuels production from hydrothermal decarboxylation of oleic acid and soybean oil over Ni-based transition metal carbides supported on Al-SBA-15

Several Ni-based transition metal carbide catalysts supported on Al-SBA-15 were studied for the hydrothermal decarboxylation of oleic acid and soybean oil to produce diesel range hydrocarbons with no added H2. The effect of pre-reduction, sub-critical, and super-critical water conditions on the catalyst activity and selectivity was investigated. Both the conversion of oleic acid and selectivity of decarboxylation products under super-critical conditions for each catalyst were about two times greater than at sub-critical conditions. In addition, the potential of these catalysts for utilizing aqueous phase reforming (APR) of glycerol for in situ H2 production to meet process demands was demonstrated. The performance of the catalysts increases with the addition of glycerol, especially for the NiWC/Al-SBA-15 catalyst. With the addition of glycerol, the NiWC/Al-SBA-15 catalyst showed greater conversion of oleic acid and selectivity to heptadecane; however, most of the oleic acid was hydrogenated to produce stearic acid. The highest conversion of oleic acid and selectivity for heptadecane was 97.3% and 5.2%, respectively. Furthermore, the NiWC/Al-SBA-15 catalyst exhibited good potential for hydrolyzing triglycerides (soybean oil) to produce fatty acids and glycerol, and then generating H2in situ from the APR of the glycerol produced. A complete conversion of soybean oil and hydrogenation of produced oleic acid were obtained over the NiWC/Al-SBA-15 at super-critical conditions.

Renewable pyridinium ionic liquids from the continuous hydrothermal decarboxylation of furfural-amino acid derived pyridinium zwitterions

Fully renewable pyridinium ionic liquids were synthesised via the hydrothermal decarboxylation of pyridinium zwitterions derived from furfural and amino acids in flow.

Deactivation of Pt Catalysts during Hydrothermal Decarboxylation of Butyric Acid

Decarboxylation of fatty acids is a path to hydrocarbon fuels from renewable biomass resources. We explored the deactivation of Pt catalysts during the hydrothermal decarboxylation of butyric acid at 350 °C and 3000 psi in a continuous flow reactor. DRIFTS spectra of the used catalyst showing characteristic absorptions at 2900 and 1500 cm–1 suggested that unsaturated hydrocarbons are responsible for catalyst poisoning. The restoration of appreciable catalyst activity due to controlled oxidation indicated that coke had formed during the decarboxylation experiment. BET measurements showed that the Vulcan XC-72R carbon support pore volume decreased from 1.41 to 0.55 cm3/g. Thus, a combination of poisoning, coking, and pore structure changes in the carbon support caused the Pt/C catalyst to deactivate over a period of 24 h on stream. The first-order deactivation rate constant for Pt/C was 0.063 ± 0.006 h–1. These results provide insight into interventions that may lead to prolonged catalyst activity for hydrothermal reactions.

Hydrothermal decarboxylation of amino acid derived imidazolium zwitterions: a sustainable approach towards ionic liquids

Ionic liquids were prepared via hydrothermal decarboxylation of zwitterionic imidazolium compounds derived from amino acids and carbohydrate related dicarbonyl compounds. Two of these ionic liquids were used successfully as solvents in the Heck reaction and for the dissolution of cellulose.