Acids In Bio-oil Research Articles

Production of Bio-gasoline by Co-cracking of Acetic Acid in Bio-oil and Ethanol

Acetic acid was selected as the model compound representing the carboxylic acids present in bio-oil. This work focuses the co-cracking of acetic acid with ethanol for bio-gasoline production. The influences of reaction temperature and pressure on the conversion of reactants as well as the selectivity and composition of the crude gasoline phase were investigated. It was found that increasing reaction temperature benefited the conversion of reactants and pressurized cracking produced a higher crude gasoline yield. At 400 °C and 1 MPa, the conversion of the reactants reached over 99% and the selectivity of the gasoline phase reached 42.79% (by mass). The gasoline phase shows outstanding quality, with a hydrocarbon content of 100%.

ChemInform Abstract: Ketonization of Carboxylic Acids: Mechanisms, Catalysts, and Implications for Biomass Conversion

Ketonization is a reaction in which two carboxylic acids convert into a ketone, carbon dioxide, and water. While this reaction once found its industrial application for acetone production, it is regaining interest for its value in the upgrading of biomass-derived oxygenates, for example, bio-oils obtained from the fast pyrolysis of biomass. Namely, ketonization is crucial to reduce the detrimental effects of carboxylic acids in bio-oil. This review addresses reaction mechanisms, families of materials that catalyze the reaction (metal oxides and zeolites), and current applications of ketonization in the upgrading of biomass-derived oxygenates. A variety of mechanisms have been proposed to explain the ketonization reaction, and these proposals are critically discussed. The role of the α-hydrogen has been proven as a critical requirement for ketonization over catalysts that are active for surface ketonization and serves as the initial basis for the discussion. The role of crucial reaction intermediates such ...

Direct Hydrogenation of Acetic Acid in Bio-Oil with the Transition and Noble Metal-Loaded Catalysts

Direct Hydrogenation of Acetic Acid in Bio-Oil with the Transition and Noble Metal-Loaded Catalysts

Ketonization of Carboxylic Acids: Mechanisms, Catalysts, and Implications for Biomass Conversion

Ketonization is a reaction in which two carboxylic acids convert into a ketone, carbon dioxide, and water. While this reaction once found its industrial application for acetone production, it is regaining interest for its value in the upgrading of biomass-derived oxygenates, for example, bio-oils obtained from the fast pyrolysis of biomass. Namely, ketonization is crucial to reduce the detrimental effects of carboxylic acids in bio-oil. This review addresses reaction mechanisms, families of materials that catalyze the reaction (metal oxides and zeolites), and current applications of ketonization in the upgrading of biomass-derived oxygenates. A variety of mechanisms have been proposed to explain the ketonization reaction, and these proposals are critically discussed. The role of the α-hydrogen has been proven as a critical requirement for ketonization over catalysts that are active for surface ketonization and serves as the initial basis for the discussion. The role of crucial reaction intermediates such ...

Co-production of furfural and acetic acid from corncob using ZnCl2 through fast pyrolysis in a fluidized bed reactor

Corncob was pyrolyzed using ZnCl2 in a pyrolysis plant equipped with a fluidized bed reactor to co-produce furfural and acetic acid. The effects of reaction conditions, the ZnCl2 content and contacting method of ZnCl2 with corncob on the yields of furfural and acetic acid were investigated. The pyrolysis was performed within the temperature range between 310 and 410°C, and the bio-oil yield were 30-60 wt% of the product. The furfural yield increased up to 8.2 wt%. The acetic acid yield was maximized with a value of 13.1 wt%. A lower feed rate in the presence of ZnCl2 was advantageous for the production of acetic acid. The fast pyrolysis of a smaller corncob sample mechanically mixed with 20 wt% of ZnCl2 gave rise to a distinct increase in furfural. A high selectivity for furfural and acetic acid in bio-oil would make the pyrolysis of corncob with ZnCl2 very economically attractive.

Catalytic conversion of carboxylic acids in bio-oil for liquid hydrocarbons production

Abstract Bio-oil must be upgraded to be suitable for use as a high-grade transport fuel. Crude bio-oil has a high content of carboxylic acids which can cause corrosion, and the high oxygen content of these acids also reduces the oil’s heating value. In this paper, acetic acid and propanoic acid were chosen as the model carboxylic acids in bio-oil. Their behavior in the production of liquid hydrocarbons during a catalytic conversion process was investigated in a micro-fixed bed reactor. The liquid organic phase from this catalytic conversion process mainly consisted of liquid hydrocarbons and phenol derivatives. Under the condition of low Liquid Hourly Space Velocity (LHSV), the liquid organic phase from acetic acid cracking had a selectivity of 22% for liquid hydrocarbons and a selectivity of 65% for phenol derivatives. The composition of the organic products changed considerably with the LHSV increasing to 3 h −1 . The selectivity for liquid hydrocarbons increased up to 52% while that for phenol derivatives decreased to 32%. Propanoic acid performed much better in producing liquid hydrocarbons than acetic acid. Its selectivity for liquid hydrocarbons was as high as 80% at LHSV = 3 h −1 . A mechanism for this catalytic conversion process was proposed according to the analysis of the components in the liquid organic phases. The pathways of the main compounds formation in the liquid organic phases were proposed, and the reason why liquid hydrocarbons were more effectively produced when using propanoic acid rather than acetic acid was also successfully explained. In addition, BET and SEM characterization were used to analyze the catalyst coke deposition.

Development of the Basis for an Analytical Protocol for Feeds and Products of Bio-oil Hydrotreatment

Methods for easily following the main changes in the composition, stability, and acidity of bio-oil as a result of hydrotreatment are presented in this paper. The methods provide the basis for the development of an analytical protocol, which can be used for bio-oil, as well as the hydrotreated products from bio-oil. The correlation to more conventional methods is provided; however, the use of these methods for the upgrading products is different than previously recognized. The differences in the properties of bio-oil and the hydrotreated products will also create challenges for the analytical protocol. Polar pyrolysis liquids and their hydrotreated products can be divided into five main groups with solvent fractionation, and the change in the proportions of the groups as a result of handling or processing is easy to follow. Over the past 10 years, this method has been successfully used for comparison of fast pyrolysis bio-oil quality and the changes during handling and storage and provides the basis of the analytical protocol presented in this paper. This paper describes the use of the method for characterization of bio-oil hydrotreatment products. A discussion of the use of gas chromatographic and spectroscopic methods is also included. In addition, fuel oil analyses suitable for fast pyrolysis bio-oils and hydrotreatment products are discussed.

Acid-catalysed reactions between methanol and the bio-oil from the fast pyrolysis of mallee bark

This paper reports the acid-catalysed reactions between methanol and the bio-oil from the fast pyrolysis of mallee bark. The study focused on the reactions of the fatty acids, esters, furans and anhydrosugars in the bio-oil with methanol at 70–170°C in the presence of a solid acid catalyst Amberlyst 70. Under the experimental conditions employed, both simple acids and fatty acids in bio-oil could be converted to either methyl esters or lactone, respectively. High molar mass esters in the original bio-oil tend to undergo transesterification to produce methyl esters. Furan aldehydes such as furfural and 5-methyl-2-furancarboxaldehyde mainly underwent acetalisation to their acetals, while 5-(hydroxymethyl)furfural (HMF) could undergo acetalisation and/or etherification. HMF including its ethers and acetals could be further converted into methyl levulinate at elevated temperatures. In addition, methyl levulinate was also found to be the product from the methanolysis of other furans such as 2-furylmethanol and the C6 anhydrosugars in bio-oil.

Hydrolysis and glycosidation of sugars during the esterification of fast pyrolysis bio-oil

Acid-catalysed esterification converts organic acids in bio-oil into useful esters. However, the conditions to carry out esterification also promote the hydrolysis of anhydro-sugars in bio-oil. This paper reports the hydrolysis and glycosidation of sugars during the esterification of bio-oil using Amberlyst-70 solid acid catalyst at 70–170°C. The bio-oil was prepared from the fast pyrolysis of mallee biomass in a fluidised-bed reactor. Our results show that sugar oligomers and levoglucosan in bio-oil can be hydrolysed to form d-glucose, which further reacts with methanol to form methyl-α-d-glucopyranoside, concurrently with the esterification of acids (e.g. formic, acetic and propionic acids) in bio-oil. The effects of other important parameters such as catalyst loading and methanol to bio-oil ratio on the hydrolysis-glycosidation of sugar compounds present in bio-oil are also reported.

Upgrading of Bio-oil by Catalytic Esterification and Determination of Acid Number for Evaluating Esterification Degree

Bio-oil was upgraded by catalytic esterification over the selected catalysts of 732- and NKC-9-type ion-exchange resins. The determination of the acid number by potentiometric titration was recommended by the authors to quantify the total content of organic acids in bio-oil and also to evaluate the esterification degree of bio-oil in the process of upgrading. We analyzed the measurement precision and calibrated the method of potentiometric titration. It was proven that this method is accurate for measuring the content of organic acids in bio-oil. After bio-oil was upgraded over 732 and NKC-9, acid numbers of bio-oil were lowered by 88.54 and 85.95%, respectively, which represents the conversion of organic acids to neutral esters, the heating values increased by 32.26 and 31.64%, and the moisture contents decreased by 27.74 and 30.87%, respectively. The accelerated aging test and aluminum strip corrosion test showed improvement of stability and corrosion property of bio-oil after upgrading, respectively.

Effect of acid catalysts and accelerated aging on the reaction of methanol with hydroxy-acetaldehyde in bio-oil

Bio-oil is a promising alternative source of energy produced from fast pyrolysis of biomass. Increasing the viscosity of bio-oil during storage is a major problem that can be controlled by the addition of methanol or other alcohols. This paper reports the results of our investigation of the reactions of short chain alcohols with aldehydes and acids in bio-oil. The reaction of methanol with hydroxyacetaldehyde (HA) to form the acetal was catalyzed by the addition of 7 x 10-4 M strong acids such as sulfuric, hydrochloric, p-toluene sulfonic acid, and methanesulfonic acid. HA formed 2,2-dimethoxyethanol (DME), and at 60 oC the equilibrium was reached in less than one hour. Smaller amounts of DME were formed in the absence of strong acid. HA, acetaldehyde, and propanal formed their corresponding acetals when reacted with methanol, ethanol, 1-propanol or 1-butanol. Esters of acetic acid and hydroxyacetic acid were observed from reactions with these same four alcohols. Other acetals and esters were observed by GC/MS analysis of the reaction products. The results from accelerated aging experiments at 90 oC suggest that the presence of methanol slows polymerization by formation of acetals and esters from low molecular weight aldehydes and organic acids.

Aging behavior and mechanism of bio-oil

On the basis of direct heating, microwave-assisted and oxygen-injected treatments were introduced to acceler-ate the aging of bio-oil, and the mass spectrometry (MS) and microscopy were employed to characterize the aged bio-oils. According to the components distribution results of bio-oil before and after the aging treatment, a preliminary aging mechanism of bio-oil was investigated. The results show that the properties and components of aged bio-oil changed significantly; the aged oil was easy to layer, and oxygen, acids or bases would accel-erate the aging. After the aging treatment, the absolute content of detectable components of aged bio-oil de-creased by 40% compared with that of the raw bio-oil, and even that of the compounds containing alkenyl and aldehyde groups was reduced to below 10%. These changes would be exacerbated by adding a certain amount of peroxyacetic acid, acids or bases. The main reactions involved in the aging process of bio-oil were polymerization, accompanied with a certain amount of condensation and esterification. Therefore, isolation from the air and removal of the acids in bio-oil could be effective in delaying and inhibiting the aging.

Esterification of Organic Acid in Bio-Oil using Acidic Ionic Liquid Catalysts

A dicationic ionic liquid C6(mim)2−HSO4 was synthesized and used as the catalyst for bio-oil upgrading through the esterificartion reaction of organic acids and ethanol at room temperature. The reaction system turned into two layers when the reaction was complete. No coke and deactivation on the catalyst were observed. The yield of upgraded oil was about 49%, and its properties were significantly improved. The higher heating value approached to 24.6 MJ/kg, the pH value increased from 2.9 to 5.1, and the moisture decreased from 29.8 to 8.2 wt %. The chemical composition of the upgraded bio-oil was analyzed with GC-MS. The results showed that organic acids were successfully converted into esters. Thus our data indicated that the dicationic ionic liquid was a promising catalyst for esterification to upgrade bio-oil.