Yields Of Furans Research Articles

Pyrolytic characteristics of hemicellulose, cellulose and lignin under CO2 atmosphere

To understand the influence of CO2 on biomass pyrolysis, the pyrolysis behavior of hemicellulose, cellulose, and lignin with CO2 were investigated by thermogravimetric analysis and a fixed-bed reactor. The detailed formation behavior of the pyrolysis products (chars, liquids, and non-condensable gases) was monitored and characterized to determine the role of CO2. The char and liquid yield of the three components were higher under CO2 than under N2 below 650 °C. For hemicellulose, more C elements were released as CO (from 1.25 mol% to 10.56 mol%) but the char yield decreased from 22.00 wt% to 10.50 wt% at 750 °C and the yield of ketones and furans was reduced. For cellulose, the yield of levoglucosans, furans, and ketones increased, but the yield of CO decreased (from 3.98 mol% to 3.10 mol% at 750 °C). For lignin, the selectivity of alkoxy phenols (G/S) increased whereas simple phenols decreased with more O elements released as CO (from 1.70 mol% to 3.41 mol% at 750 °C). For solid char, all samples exhibited more CO and COO groups with CO2 at 750 °C.

In-situ hydrodeoxygenation of furfural to furans over supported Ni catalysts in aqueous solution

In-situ hydrodeoxygenation of furfural as a representative component in bio-oil was investigated in aqueous solution over supported Ni catalysts, for preparing furans as an antiknock additive. The addition of methanol, ethanol, or isopropanol was found inhibitive to coke formation at 220 °C. When using methanol as the hydrogen donor and coke inhibitor, the support in mesoporous structure with moderate acidity was more favorable to the conversion of furfural and to the formation of furans. An increased loading amount of Ni facilitated the generation of deep hydrogenated products. The conversion of furfural could hardly be changed under different methanol to water ratios, while the product distribution varied remarkably. Under optimized conditions, the summary yield of furan and 2-methylfuran reached to above 85%. On the basis of optimized reaction conditions, the in-situ hydrodeoxygenation of an eight-component synthetic bio-oil was tested, and the results verified the adaptability of the method for conversion of bio-oil.

Products distribution and generation pathway of cellulose pyrolysis

Pyrolysis was one of the most effective ways for the clean use of biomass and biomass that constitutes a huge annual production. In order better utilize biomass, this study infers the pyrolysis mechanism of cellulose, cellobiose, β-D-glucopyranose and levoglucosan by Py-GC-MS (Pyrolysis-gas chromatography-mass spectrometry) and in-situ infrared spectroscopy. Pyrolysis products of cellulose included dehydrated saccharides, furans, small molecules, furanones, benzenes, and cyclopentanones. The first three categories were the main products. Saccharides had the highest yield in cellulose pyrolysis products. The yield of furans in pyrolysis products of cellobiose was higher than that in cellulose and β-D-glucopyranose. The highest yield of small molecules, such as acetaldehyde and methyl glyoxal, was found in pyrolysis products of β-D-glucopyranose. There was a competitive relationship among the production of saccharides, furans and small molecules in the primary pyrolysis. And the furans and small molecules were also the products of the secondary pyrolysis of saccharides. Combined with in situ infrared analysis, 32 generation pathways of the 27 main products detected from Py-GC-MS were given; this provides a theoretical basis for subsequent research on targeted pyrolysis manufacturing target products.

A flexible Cu-based catalyst system for the transformation of fructose to furanyl ethers as potential bio-fuels

Biomass-derived furanyl ethers, such as 5-alkoxymethylfurfurals (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs), can be employed as promising biofuels or additives. The development of multifunctional catalysts for the efficient production of furanyl ethers from sugars through 5-hydroxymethylfurfural (HMF) as an intermediate is highly desirable but challenging, because multiple reactions including dehydration, etherification and hydrogenation get involved and the side reaction of sugars and HMF to form humins is inevitable. In this contribution, we found that the introduction of CuO resulted in the generation of Lewis acid sites at the cost of Bronsted acid sites over CuO-USY catalysts through the formation of Al-O-Cu(II) species. The dispersity of CuO particles and the amount of Lewis acid sites could be manipulated by adjusting the loading of CuO. If 5 wt% CuO was supported on USY zeolite to give a CuO(5)-USY catalyst, CuO particles with a high dispersity (36.4%) afforded abundant Lewis acid sites (457.1 μmol/g). Lewis acid over CuO(5)-USY greatly promoted the acid-catalyzed dehydration of fructose to HMF and HMF etherification to AMFs, resulting in a HMF yield up to 86.2% from fructose and AMFs yields greater than 90% from HMF. Interestingly, a combination of CuO(5)-USY and a small amount of metallic Cu powder was able to offer desirable BAMFs yields by the reductive etherification of HMF under hydrogen atmosphere. As a result, 5-methoxymethylfurfural (MMF) of 79.6% and 2,5-bis(methoxymethyl)furan (BMMF) yield of 74.5% were achieved from fructose through HMF as an intermediate in the presence of CuO(5)-USY alone or with metallic Cu as a co-catalyst. Therefore, the above Cu-based catalyst system holds the promise to flexibly produce a family of AMFs or BAMFs from fructose via a facile two-step approach.

Oxidative reactions of sulfinyl dienes as an entry to functionalized carbohydrate-like products and furans

Oxidative cleavage (OsO4/NaIO4) of a monoprotected dihydroxy sulfinyl diene affords a lactol, readily transformed into a sulfinyl pyranose. Alternatively, base promoted intramolecular cyclization of a lactol derived carbamate to a bicyclic oxazolidinone followed by simple transformations leads to an amino sulfonyl pyranose. In contrast, ozonolysis of a variety of hydroxy sulfinyl dienes leads to fair yields of 3-sulfinyl furans in a single step.

Effects of alkali and alkaline earth metals on the co-pyrolysis of cellulose and high density polyethylene using TGA and Py-GC/MS

The effects of the type and content of alkali/alkaline earth metals (AAEMs) on the co-pyrolysis of cellulose/high density polyethylene (HDPE) were studied using TGA and Py-GC/MS. AAEMs showed different effects on the decomposition characteristics of cellulose/HDPE mixtures. During cellulose/HDPE co-pyrolysis, AAEMs present in char could act as a base catalyst, with different catalytic effect on products distribution depending on the types of AAEMs. Na showed stronger catalytic cracking effect to promote alkenes formation compared to the use of K, Ca, and Mg. The comparison of experimental and calculated products distributions of raw cellulose/HDPE confirmed the existence of synergistic effect, which facilitated the cleavage of glycosidic linkages to form anhydrosugars and promoted the scission of HDPE chains to produce hydrocarbons. The effect of potassium on this synergy was also investigated. With increased potassium content, the yields of anhydrosugars and hydrocarbons decreased while the yields of furans and ketones increased, suggesting that potassium inhibited the cleavage of glycosidic bonds and promoted ring-opening reactions. This indicated that addition of potassium inhibited the synergy between cellulose and HDPE.

Preparation of furans from catalytic conversion of corn stover in H2O–THF co-solvent system – The effects of acids combined with alkali metal cations

Abstract The preparation of furans from catalytic conversion of corn stover is investigated in H2O–THF (tetrahydrofuran) co-solvent system, and the effects of Bronsted acids (H2SO4, HCl, HNO3) combined with alkali metal cations (Li+, Na+, K+) are studied systematically. It is found that the effect of individual acid in promoting the summary yield of 5-hydroxymethylfurfural (HMF) and furfural (FF) can be ordered as Cl− > SO42− > NO3−. When combined with a salt, the anion effect can be ranked in SO42− > Cl− > NO3−, both for the HMF yield and the summary yield of furans. Based on the best anion of SO42−, the impacts of the combined cations can be finely ranked as Na+ > K+ > Li+. For the system with Cl−, it ranks in K+ > Li+ > Na+ for the HMF yield or the summary yield of furans. The performance of NO3− is so poor that no liquid product can be detected when any alkali metal cations is combined with HNO3. The performance of H2SO4/Na2SO4 is the best among 9 tested combined catalysts, and the yield of HMF and FF from corn stover conversion under optimized conditions are 76% and 81% respectively.

Bridging the relationship between hydrothermal pretreatment and co-pyrolysis: Effect of hydrothermal pretreatment on aromatic production

The effect of hydrothermal pretreatment (HTP) on the biomass structure and aromatic production in the catalytic co-pyrolysis process was investigated in this study. Fundamental characteristic analysis indicated that HTP removed most of the hemicellulose and some oxygen, enhancing the hydrogen-to-carbon effective ratio (H/Ceff) of biomass. X-ray diffraction, Fourier-transform infrared spectroscopy, and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance analysis revealed that HTP mainly interrupted unstable chemical bonds (acetyl groups, glycosidic bonds, and ether linkage in lignin) and changed the biomass crystallinity. Furthermore, HTP remarkably removed alkalis and alkali earth metals (AAEM) from the biomass. To determine the effect of HTP on co-pyrolysis, individual pyrolysis of raw and pretreated corncob was carried out. Results showed that HTP significantly enhanced yields of levoglucosans and furans, both of which are important intermediates for aromatic formation during co-pyrolysis. HTP remarkably increased the aromatic contents of bio-oil in the co-pyrolysis of different corncob samples and polyethylene. The influence of HTP on aromatic production mainly included AAEM removal, hemicellulose decomposition, furan formation, and H/Ceff increments in the pretreated biomass. Thus, HTP has great potential in improving aromatic production during co-pyrolysis of biomass and polyethylene.

Sulfonated tobacco stem carbon as efficient catalyst for dehydration of C6 carbohydrate to 5-hydroxymethylfurfural in γ-valerolactone/water

A carbon solid acid was made by grafting benzenesulfonic acid groups on the tobacco stem-derived porous carbon, which was prepared from waste tobacco stem by simple carbonization. The catalyst was characterized by scanning electron microscope (SEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), pyridine FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The catalyst exhibited excellent catalytic activity for 5-hydroxymethylfurfural (HMF) production from fructose and glucose in γ-valerolactone/water solvent, and high yields of HMF reached 93.7 and 43.8%, respectively. In addition, the high yields of total furans derived from fructose and glucose reached 96.8 and 54.1%, respectively. The benzenesulfonic acid group grafted onto the surface of inner pores of carbon allowed reusing the catalyst for at least five runs without obvious activity reduction. The good performance of the tobacco stem-derived carbon solid acid was determined by the unique surface active sites, such as high density of Brønsted acid, Lewis acid sites, oxygen-containing weak acidic sites and protonated nitrogen-containing functional groups. This study offered a promising approach for efficient carbohydrate conversion.

Conversion of Sugars and Biomass to Furans Using Heterogeneous Catalysts in Biphasic Solvent Systems.

Within the last decade, interest in using biphasic systems for producing furans from biomass has grown significantly. Biphasic systems continuously extract furans into the organic phase, which prevents degradation reactions and potentially allows for easier separations of the products. Several heterogeneous catalyst types, including zeolites, ion exchange resins, niobium‐based, and others, have been used with various organic solvents to increase furan yields from sugar dehydration reactions. In this minireview, we summarized the use of heterogeneous catalysts in biphasic systems for furfural and 5‐hydroxymethylfurfural production from the past five years, highlighting trends in chemical and physical properties that effect catalytic activity. Additionally, the selection of an organic solvent for a biphasic system is extremely important and we review and discuss properties of the most commonly used organic solvents.

Two Possible Side Reaction Pathways during Furanic Etherification

The revealing mechanism of side reactions is crucial for obtaining theoretical yield in industrialization when 2,5-bis(methoxymethyl)furan (BMMF) yield is above 95%. By-products catalyzed by the conventional ZSM-5 (C-ZSM-5) and hierarchical porous ZSM-5 (HP-ZSM-5) catalytic systems were different, and some key by-products were identified. Thus, possible pathways were proposed, which helps to further improve BMMF selectivity. Additionally, HP-ZSM-5 exhibited quicker reaction rate, higher BMMF yield and selectivity, and slower deactivation process. The relatively weak acidity of HP-ZSM-5 suppresses the ring-opening reaction and subsequent side reactions, and introduction of mesopores improves mass transport and slightly increases hydration of 2,5-bis(hydroxymethyl)furan (BHMF).

Catalytic Pyrolysis of Pinus densiflora Over Mesoporous Al2O3 Catalysts

The thermal and catalytic pyrolysis of Pinus densiflora (P. densiflora) were performed to test the catalytic cracking efficiency of two mesoporous Al2O3 catalysts with different surface areas. Thermogravimetric analysis (TGA) of P. densiflora showed that the differential TG (DTG) peak heights obtained from catalytic pyrolysis were smaller than those of non-catalytic pyrolysis due to the conversion of the reaction intermediates to coke. Pyrolyzer-gas chromatography/mass spectrometry analysis/flame ionization detection (Py-GC/MS/FID) suggested that using the Al2O3 catalysts, the yields of phenols and levoglucosan decreased with a concomitant increase in the yields of aldehydes, alcohol, ketones, and furans. Between the two catalysts, Al2O3-B prepared by spray pyrolysis showed higher cracking efficiency than Al2O3-A prepared by hydrothermal method because of its larger surface area.

Catalytic co-pyrolysis of cellulose and polypropylene over all-silica mesoporous catalyst MCM-41 and Al-MCM-41

Fast pyrolysis is one of the most economical and efficient technologies to convert biomass to bio-oil and valuable chemical products. Co-pyrolysis with hydrogen rich materials such as plastics over zeolite catalysts is one of the significant solutions to various problems of bio-oil such as high oxygen content, low heat value and high acid content. This paper studied pyrolysis of cellulose and polypropylene (PP) separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41. The pyrolysis over different heating rates (10K/min, 20K/min, 30K/min) was studied by Thermogravimetry Analysis (TGA) and kinetic parameters were obtained by Coats-Redfern method and isoconversion method. TG and DTG data shows that the two catalysts advance the pyrolysis reaction of PP significantly and reduce its peak temperature of DTG curve from 458°C to 341°C. The activation energy of pyrolysis of PP also has a remarkable reduction over the two catalysts. Py-GC/MS method was used to obtain the product distribution of pyrolysis of cellulose and PP separately and co-pyrolysis of cellulose and PP over MCM-41 and Al-MCM-41 at constant temperature of 650°C. Experiment results proved that co-pyrolysis with PP bring significant changes to the product distribution of cellulose. Oxygenated compounds such as furans are decreased, while yields of olefins and aromatics increase greatly. The yield of furans increases with the catalysis of MCM-41 as for the pyrolysis of cellulose and co-pyrolysis, while the yield of olefins and aromatics both experience significant growth over Al-MCM-41, which can be explained by the abundant acid centers in Al-MCM-41.

Selective Oxidation of 5-(Hydroxymethyl)furfural to Furan-2,5-dicarbaldehyde with Sodium Nitrite in Phosphoric Acid

5-(Hydroxymethyl)furfural is readily oxidized to furan-2,5-dicarbaldehyde with sodium nitrite in phosphoric acid at room temperature (25°C). The best selectivity for furan-2,5-dicarbaldehyde is achieved using 2.5 equiv of sodium nitrite with respect to the substrate. In this case, nearly quantitative yield of furan- 2,5-dicarbaldehyde is attained in 1 h, the substrate conversion being complete. Due to high selectivity in combination with low cost and toxicity of phosphoric acid, the system NaNO2–H3PO4 is more convenient than NaNO2–CF3COOH for the preparative synthesis of furan-2,5-dicarbaldehyde.

Catalytic fast co-pyrolysis of bamboo residual and waste lubricating oil over an ex-situ dual catalytic beds of MgO and HZSM-5: Analytical PY-GC/MS study

Catalytic fast co-pyrolysis (co-CFP) of bamboo residual (BR) and waste lubricating oil (WLO) over dual catalytic beds of MgO and HZSM-5 were carried out in an analytical PY-GC/MS. The effects of pyrolysis temperature, catalyst types, HZSM-5/MgO mass ratio and WLO percentage on products distribution and selectivities of aromatics were investigated. Experimental results revealed that 600°C promoted the total peak area of volatile matters and accelerated the yields of furans and phenols. Compared to HZSM-5, MgO exhibited pronounced deacidification via ketonization and aldol condensation reactions as the minimum yield of acids (2.116%) and the maximum yield of ketones (28.805%) could be obtained. Furthermore, given the selectivity of phenols, MgO not only spurred the increase of overall phenols yield, but also facilitated the selectivity of light phenols like phenol and 4-methyl-phenol. With respect to the co-CFP of BR and WLO, a HZSM-5/MgO mass ratio of 3:2 largely accelerated the yield of aromatics via Diels-Alder reaction. Simultaneously, the WLO percentage played a vital role in the yield of hydrocarbons (i.e. aromatics+olefins & alkanes), and the maximum yield (70.305%) could be attained at the percentage of 60% as a function of significant activation of hydrocarbon pool.

Hydrodeoxygenation of 2-furyl methyl ketone as a model compound of algal Saccharina Japonica bio-oil using iron phosphide catalyst

We report the hydrodeoxygenation of 2-furyl methyl ketone over iron phosphide catalyst to reform the C6 structure into C7 compounds with higher octane ratings. High conversion and yield were achievable from the reaction at 400°C when 5wt% Fe2P/γ-Al2O3 catalyst calcined at 600°C was used. High calcination temperature and reaction temperature are the favorable conditions to achieve high conversion in the reaction. The highest conversion of 92.60% was achieved with 2-allyl furan yield of 79.34% and methyl cylcohexane yield of 13.26% in the liquid phase and 100% carbon dioxide in the gas phase.

Role of Potassium Exchange in Catalytic Pyrolysis of Biomass over ZSM-5: Formation of Alkyl Phenols and Furans

Catalytic fast pyrolysis of biomass with ZSM-5 type zeolites is a commonly considered in situ upgrading technique for the production of partially deoxygenated bio-oils. The acidity and structure of ZSM-5 catalysts favor the production of aromatic hydrocarbons from oxygenates present in the pyrolysis vapors, such as acids, anhydrosugars, ketones and aldehydes. However, these acid catalyzed deoxygenation pathways remove functional groups from the aromatic ring structure, which makes the liquid bio-oil more amenable to processing in current petroleum refineries while subsequently decreasing the value of the compounds as industrial chemical feedstocks. The observation of improved yields of alkyl phenols and furans during catalyst deactivation suggests a method for tuning the product distribution by altering the parent zeolite catalyst via changes in acidity and/or incorporation of alkali metals known to accumulate on the catalyst during pyrolysis. Here, we report the catalytic fast pyrolysis of three biomass ...

Catalytic co-pyrolysis of biomass and polyethylene in a tandem micropyrolyzer

In the present study, catalytic fast co-pyrolysis of biomass and polyethylene (PE) was studied in a tandem micro-pyrolyzer using HZSM-5 as the catalyst. Cellulose, xylan and milled wood lignin were co-pyrolyzed with PE in both the presence and absence of catalyst to investigate the interaction between biomass and PE during thermal depolymerization and the following catalytic upgrade of the pyrolysis vapor. Co-pyrolysis with PE was found to increase the yields of furans and double anhydrosugar from cellulose up to 45%. Co-pyrolysis of xylan and PE increased not only the yields of furans and double anhydrosugar, but also the yield of acetic acid by 45%. Depolymerization of lignin was strongly promoted by PE as the yields of various phenolic monomers increased up to 43%. It was also found that the amounts of pyrolysis char and carbon oxides produced from biomass compounds decrease when co-pyrolyzed with PE. The presence of cellulose, xylan or lignin, on the other hand, facilitated depolymerization of PE by increasing the yields of olefins and alkanes with shorter carbon chains. When the pyrolysis vapor was upgraded by HZSM-5 zeolite catalyst, synergy increased the yields of hydrocarbons and suppressed the formation of catalytic coke, compared to when biomass compounds and PE were independently converted. During catalytic co-pyrolysis of cellulose and PE, the increase of the aromatic hydrocarbon yield was accompanied by the decrease in the selectivity of ethylene and propylene and no significant increase of total aliphatic hydrocarbons (i.e., the sum of olefins and alkanes), suggesting Diels–Alder reaction as the dominant reaction. On the other hand, catalytic co-pyrolysis of PE with xylan or lignin increased both the yields of aromatic and aliphatic hydrocarbons. The yield of alkanes decreased most significantly in the mixture of lignin and PE, suggesting that phenolic compounds act as strong hydrogen acceptors when they are deoxygenated. In the present study, red oak and PE were also catalytically co-pyrolyzed and the effects of pyrolysis temperature and catalyst temperature on product distribution and the extent of synergy were investigated. Both higher pyrolysis temperature and catalyst temperature were able to reduce the formation of catalytic coke and increase the yield of aromatic hydrocarbons monotonically. However, the maximum yield of aliphatic hydrocarbons was obtained at the intermediate pyrolysis temperature or catalyst temperature. Synergy between biomass and PE was consistent, regardless of changing pyrolysis temperatures. In comparison, the synergy became less significant when catalytic temperature was increased.

Effect of Torrefaction on Biomass Physicochemical Characteristics and the Resulting Pyrolysis Behavior

This study investigated the changes in biomass physicochemical characteristics during torrefaction and its influence on the resulting pyrolysis behavior. Torrefaction reduced biomass hemicellulose content and increased the high heating value and the mass energy density. Two-dimensional perturbation correlation analysis, based on diffuse reflectance infrared Fourier transform spectroscopy, showed that the main reactions occurring during torrefaction were dehydration, deacetylation, and cleavage of ether linkages. A distributed activation energy model with three Gaussian functions and weighting factors was used to study the pyrolysis kinetics, and it was found that as the torrefaction temperature increased, the contribution of lower activation energy parallel reactions to devolatilization decreased, while condensation became more important. The yields of acids and furans from the pyrolysis of torrefied biomass also decreased. The lignin side branches were cleaved during high temperature torrefaction, result...

Liquid-Phase Catalytic Transfer Hydrogenation of Furfural over Homogeneous Lewis Acid-Ru/C Catalysts.

The catalytic performance of homogeneous Lewis acid catalysts and their interaction with Ru/C catalyst are studied in the catalytic transfer hydrogenation of furfural by using 2-propanol as a solvent and hydrogen donor. We find that Lewis acid catalysts hydrogenate the furfural to furfuryl alcohol, which is then etherified with 2-propanol. The catalytic activity is correlated with an empirical scale of Lewis acid strength and exhibits a volcano behavior. Lanthanides are the most active, with DyCl3 giving complete furfural conversion and a 97 % yield of furfuryl alcohol at 180 °C after 3 h. The combination of Lewis acid and Ru/C catalysts results in synergy for the stronger Lewis acid catalysts, with a significant increase in the furfural conversion and methyl furan yield. Optimum results are obtained by using Ru/C combined with VCl3 , AlCl3 , SnCl4 , YbCl3 , and RuCl3 . Our results indicate that the combination of Lewis acid/metal catalysts is a general strategy for performing tandem reactions in the upgrade of furans.