Bio-oil Aqueous Fraction Research Articles

Energy and economic analysis of alternatives for the valorization of hydrogen rich stream produced in the aqueous phase reforming of pyrolysis bio-oil aqueous fraction

Aqueous phase reforming has been explored for renewable H2 production from waste biomass. Promising results have been reported for pyrolysis bio-oil aqueous fractions (AFB), but economical assessments are needed to determine process feasibility, which requires both energy consumption minimization and optimal H2 valorization. This work compares different alternatives using process simulation and economic evaluation computational tools. Experimental results and a specific thermodynamic model are used to set mass balances. An adequate heat integration allows to reduce the process energy demand, covering the 100 % of the reactor duty. Optimal H2 unit cost is achieved if part of the produced H2 is valorized for energy self-covering and the rest is commercialized. Renewable H2 net production of c.a. 3.3 kgH2/m3 of treated AFB at a preliminary 1–2 €/kg unit cost is estimated, which can be considered as competitive with green H2, even though a case of diluted AFB is considered.

Valorization to hydrogen of bio-oil aqueous fractions from lignocellulosic biomass pyrolysis by aqueous phase reforming over Pt/C catalyst

Aqueous phase reforming was studied for the valorization to hydrogen of the aqueous fraction of bio-oil from lignocellulosic biomass pyrolysis. Aqueous phase reforming was carried out at 220 °C with a 3 % wt. Pt/carbon catalyst and an aqueous fraction of bio-oil feed containing 1 % wt. of organic matter. Binary and multicomponent mixtures representing aqueous fractions of bio-oil were studied. Strong hydrogen production dependence on aqueous fraction of bio-oil composition was evidenced. Higher processability was obtained for aqueous fractions of bio-oil rich in levoglucosan and hydroxyacetone, reaching a hydrogen production close to 40 mmol per gram of organic carbon, whereas furfural and acetic acid hampered reforming. A significant influence of minority components such as methanol and, particularly, formic acid, was observed. These components improved reforming of the whole multicomponent mixture, showing that blending with biorefinery fractions rich in them can improve the applicability of aqueous phase reforming. The catalyst exhibited stable activity and hydrogen production after 5 reaction cycles and more than 20 h. An increase in selectivity was observed during cycles 2 and 3, which was studied by characterization of fresh and used catalysts to show structure-selectivity relationships. No significant variation of Pt2+/Pt0 and metal particle mean diameter were observed, but Pt nanoparticles underwent morphological changes leading to higher prevalence of low coordination sites, in particular step-edge sites on the particle surface, resulting in higher hydrogen production. Temperature programmed desorption and oxidation analysis showed a cumulative deposition of reaction byproducts on the catalyst surface that contributed to loss of activity.

Steam reforming of the simulated aqueous fraction of bio-oil based on pre-reforming with dolomite

Hydrogen production by steam reforming of a simulated aqueous bio-oil (consisting of acetic acid, acetone, furfural and phenol) in a two-stage system with dolomite followed by NiO/CeO2-Al2O3 catalyst (with 5, 10 and 15 wt% Ni) was studied, and the results were compared. The increase in hydrogen yield obtained in the two-stage system with respect to the one-stage system was higher (up to 9.09%) for the less active catalyst (the one-stage with 5wt.%Ni). The higher reforming temperature and Steam/Carbon were beneficial for the production of hydrogen and the gas composition was mostly affected by the pre-reforming temperature, with the hydrogen yield and the hydrogen composition were 65.92% and 67.15%, while the pre-reforming temperature were kept at 650 °C, the reforming temperature were kept at 700 °C, Steam/Carbon = 3 and the catalyst was 15NiO/CeO2-Al2O3. Subsequently, the removal of phenol was promoted by pre-reforming with dolomite and it was beneficial to the reduction of coke deposition. Deactivated catalysts (characterized by XRD, TG, TEM and SEM) showed the coke deposition on the surface of 15NiO/CeO2-Al2O3 catalyst in the two-stage system was significantly lower than that in one-stage system, 5.12% and 7.15%, respectively. The filamentous coke and amorphous coke formed on the catalyst used by two-stage reforming were more beneficial to delay the catalyst deactivation than the amorphous carbon formed on the one-stage system. In this study, the stability of Ni-based catalyst was enhanced, which provided a reference for the optimization of hydrogen production process by steam reforming of aqueous fraction of bio-oil.

Aqueous-phase reforming of water-soluble compounds from pyrolysis bio-oils

Aqueous-phase reforming (APR) of model compounds of bio-oil aqueous fraction (AFB) was studied at different operating conditions. Substrate conversion, carbon-to-gas yield (CCgas) and hydrogen and alkanes production were evaluated. Levoglucosan, hydroxyacetone, furfural and acetic acid were selected as representative of AFB and tested in batch APR at different concentrations (1–5 %wt.), temperatures (175–220 °C) and reaction times (0.5–4 h), using 3% (wt.) Pt/CB catalysts. Best results were obtained at 220 °C and 1%, with 70–90% substrate conversions, 45–70% CC gas and hydrogen production up to 50 mmol per gram of total organic carbon (TOC). Catalyst stability was checked in APR of levoglucosan during five successive 4 h reaction cycles. The catalyst exhibited high stability, CCgas remained constant and hydrogen production increased and became stable after first reaction cycle with only a slight decrease of TOC conversion. The catalyst with well dispersed metal phase and high contribution of nanoparticles smaller than 2 nm showed a higher production of hydrogen. APR was proved to be a feasible option for the valorisation of AFB.

Hydrogen production via steam reforming of small organic compounds present in the aqueous fraction of bio-oil over Ni-La-Me catalysts (Me = Ce, Ti, Zr)

Hydrogen production via steam reforming of small organic compounds present in the aqueous fraction of bio-oil over Ni-La-Me catalysts (Me = Ce, Ti, Zr)

Steam Reforming of the Model Compounds in the Aqueous Fraction of Bio-Oil Based on Pre-Reforming Over Dolomite

Steam Reforming of the Model Compounds in the Aqueous Fraction of Bio-Oil Based on Pre-Reforming Over Dolomite

Extraction of phenols from bio-oil aqueous fraction by hydrophobic ionic liquids

Acetic acid, phenol, guaiacol and 4-methylguaiacol in bio-oil aqueous fraction were extracted and separated experimentally with the choice of hydrophobic ionic liquid [Bmim][NTf2] as extractant. The effects of extraction time and extractant dosage on the extraction efficiency were explored. With the help of density functional theory (DFT) calculations, the interaction mechanism between [Bmim][NTf2] and phenol was also clarified. The results showed that under the optimal extraction condition (mIL/mW = 0.4, extraction time = 5 min), the extraction efficiencies of acetic acid, phenol, guaiacol and 4-methylguaiacol in the aqueous fraction were 2.71%, 95.41%, 92.04%, and 97.98%, respectively. It was indicated that [Bmim][NTf2] had better selectivity and superior extraction efficiency for phenols in bio-oil aqueous fraction. The results of DFT calculation demonstrated that the strong hydrogen bonding interaction as well as weak vdW interaction between [Bmim][NTf2] and phenols played an important role in extraction and dephenolization of bio-oil aqueous fraction. The phenols in [Bmim][NTf2] can be effectively removed by alkali washing treatment to achieve recovery of [Bmim][NTf2] and next high efficiency extraction.

Influence of the Ni-Co/Al-Mg Catalyst Loading in the Continuous Aqueous Phase Reforming of the Bio-Oil Aqueous Fraction

The effect of catalyst loading in the Aqueous Phase Reforming (APR) of bio-oil aqueous fraction has been studied with a Ni-Co/Al-Mg coprecipitated catalyst. Because of the high content of water in the bio-oil aqueous fraction, APR could be a useful process to convert this fraction into valuable products. Experiments of APR with continuous feeding of aqueous solution of acetol, butanol and acetic acid as the only compound, together with a simulated and a real aqueous fraction of bio-oil, were carried out. Liquid products in the liquid effluent of the APR model compounds were quantified and the reaction pathways were revised. The increase of catalyst loading produced an increase of gas production and a gas with higher alkanes content. Acetol was the compound with the highest reactivity while the conversion of acetic acid was very low. The presence of acetic acid in the feed caused catalyst deactivation.

Is pyrolysis bio-oil prone to microbial conversion into added-value products?

In view of the potential application of pyrolysis-based biotechnologies, it is crucial to look for novel microorganisms able to convert pyrolysis-derived products, in particular bio-oil water-soluble constituent, into valuable compounds. For the first time, this paper proposed a survey on a collection of bacterial, yeast, and fungal strains with well-known industrial properties as well as new bacterial isolates in order to select microbes able to both tolerate bio-oil inhibitors and convert bio-oil into valuable products. This survey found that bio-oil aqueous phase (BOAP) obtained from intermediate pyrolysis could be metabolized as it is by fungal strains whereas several dilutions are needed to do not hamper cell viability of many tested yeast and bacterial isolates.To process BOAP into valuable products, the yeast Saccharomyces cerevisiae L13, selected as the most industrially relevant tested strain, was adopted to convert bio-oil aqueous fraction hydrolysate into ethanol without any detoxification step. The fermenting performances were much greater than those of the benchmark yeast strain and S. cerevisiae L13 proved to be a strong candidate for bioethanol production from BOAP hydrolysates.This study demonstrated that the search for microorganisms is a promising approach to the future development of pyrolysis oil-based biorefinery platforms.

Coke evolution in simulated bio-oil aqueous fraction steam reforming using Co/SBA-15

This paper studies Co/SBA-15 catalyst deactivation during the steam reforming of model compounds from the aqueous fraction of bio-oil coming from biomass HTL. We observed how deactivation took place in two clearly differentiated stages. In the first one (TOS < 20 h), where conversion decreased strongly, Co sintering deduced from XRD and, pore blockage by coke deposition were observed. At this first stage, coke seemed to be filamentous and some encapsulated Co particles could be appreciated by TEM. The encapsulating coke reduced the number of accessible centers to catalyze the reforming reaction. In the second stage (TOS > 20 h), filamentous coke was also observed but more condensed and therefore more aromatic, as verified by higher C/H ratio determined by elemental analysis. In this stage, despite the amount of coke deposited was growing, no drop on specific surface area was observed. Besides, since no peaks corresponding to cobalt oxides were detected in the XRD patterns, catalyst deactivation cannot be attributed to metallic active sites oxidation. The t-Student statistical analysis showed that Co/SBA-15 catalyst deactivation is mainly affected by the amount of coke deposited and its C/H ratio.

Selective generation of aromatic hydrocarbons from hydrotreating-cracking of bio-oil light fraction with MOx modified HZSM-5 (M = Ga, Mo and Zn)

The upgrading of highly unsaturated bio-oil by zeolite cracking suffers from severe catalyst deactivation due to the carbonaceous deposition. Therefore, the dual-stage hydrotreating-cracking process is developed for more stable operation. In this work, to further promote the generation of aromatic hydrocarbon in a hydrotreating-cracking process cofeeding bio-oil light fraction and methanol, the cracking catalyst HZSM-5 was modified by MOx (M = Ga, Mo and Zn). Compared with the blank HZSM-5, the promotion of aromatic hydrocarbon production by MoO3/HZSM-5 was mainly owing to the enhanced selective conversion of intermediate light alkenes to aromatics, while those by Ga2O3/HZSM-5 and ZnO/HZSM-5 were attributed to both the re-activation of hydrotreating-derived CH4 and the intensified selective aromatization of alkenes. Meanwhile, raising cracking temperature decreased the yield of aromatic hydrocarbon but favored the production of gases. Ga2O3/HZSM-5 was the most effective catalyst for aromatic hydrocarbon production and 400 °C was a suitable cracking temperature, under which the upgrading of a bio-oil aqueous fraction achieved the oil phase yield of above 22% with the aromatic hydrocarbon content of above 93%.

Enhanced aromatic hydrocarbon production from bio-oil hydrotreating-cracking by Mo-Ga modified HZSM-5

Because the bio-oil is highly unsaturated, the upgrading of bio-oil by zeolite cracking faces the problem of severe carbonaceous deposition on catalysts. Therefore, the dual-stage hydrotreating-cracking process is considered to be more practical for bio-oil upgrading. This work focused on a bio-oil hydrotreating-cracking process cofed with methanol, and the modification of cracking catalyst for enhanced aromatic hydrocarbon generation was investigated. Mo-Ga/HZSM-5 exhibited better performance than HZSM-5 on aromatic hydrocarbon production, owing to the synergistic effect of Mo species, Ga2O3 and acidic sites on HZSM-5. In the cracking stage, this synergistic effect activated the hydrotreating-derived CH4 and thereby enabled it to participate in aromatization reactions; and it also facilitated the conversion of alkene intermediates to aromatic hydrocarbons by inhibiting C2-C4 alkane formation and promoting aromatization reactions. 5Mo-2Ga/HZSM-5 was an efficient cracking catalyst in hydrotreating-cracking, both for the simulated bio-oil fraction and the actual bio-oil aqueous fraction.

Agglomerated Co–Cr/SBA-15 catalysts for hydrogen production through acetic acid steam reforming

Hydrogen produced from renewable resources is becoming interesting as an alternative to conventional fossil fuels. Co-based catalysts have been reported for their active role in steam reforming of acetic acid as the main model compound of bio-oil aqueous fraction. In the present work, a series of Co–Cr/SBA-15 extrudates were prepared by varying the binder (bentonite) content and particle size in order to get catalyst particles suitable to be used in a steam reformer at industrial scale. Catalysts were characterized by N2 physisorption, ICP-AES, TEM, SEM, XRD and H2-TPR. The physicochemical characterization results showed that no remarkable changes occurs after the extruding process of the powdered sample, except for the particle size and mechanical strength. Acetic acid steam reforming tests were done at 600 °C and WHSV = 30.1 h−1 varying the feed flow rate and the catalysts particle size in order to study the influence of internal and external diffusion limitations. Extruded particles with an effective diameter of 1.5 mm and 30 wt% of bentonite get similar conversion and hydrogen selectivity than powder sample. Besides, the agglomerated catalysts are also stable up to 12 h of TOS.

Use of montmorillonite to recover carboxylic acids from aqueous medium

In this work, it was investigated the use of montmorillonite as a trap to recover small carboxylic acids from aqueous medium. TOC and titration analyses showed remarkable uptake of organic acid molecules, e.g. 46, 49, 9 and 16 mmol g−1 of acetic, propionic, citric and lactic acids, respectively (1.4–3.6 gacid gclay−1), in concentrations up to 4 mol L−1. XRD, TG-MS and BET indicated that acetic and propionic acids can be easily recovered from montmorillonite, producing some delamination of the clay mineral with the formation of mesopores and increasing the specific surface area to 83 m2 g−1. Non-volatile citric and lactic acids are also efficiently removed from aqueous solution. Although the uptake mechanism of the acids by the clay is not clear, XRD and FTIR results indicate a possible intercalation process that strongly affects the SiO tetrahedral layer of Mt. Preliminary experiments using a strongly acidic aqueous fraction of bio-oil indicated that montmorillonite can be used to recover small organic acids from the complex mixture by selectively trapping.

Aqueous-phase reforming of bio-oil aqueous fraction over nickel-based catalysts

Abstract Aqueous-phase reforming (APR) is a quite new technology for the production of hydrogen and light hydrocarbons from aqueous-organic mixtures in a single-stage process. This manuscript analyzes the APR of representative model compounds of bio-oil aqueous fraction, including acetic acid, ethanol, 1-hydroxypropan-2-one (acetol) and benzene-1,2-diol (catechol), as well as a mixture of all of them. The APR experiments were conducted at 230 °C and 3.2 MPa over three different Ni-based catalysts, including spinel NiAl2O4, and supported Ni/CeO2-γAl2O3 and Ni/La2O3-αAl2O3. The reactivity of the model compounds varied largely in the order: acetol > ethanol > catechol > acetic acid, whereas the H2 production decreased in the following order: ethanol ≫> acetol > acetic acid > catechol. Based on the product distribution obtained, the reaction pathways in the APR of each model compound have been proposed. In the APR of the mixture, the Ni/La2O3-αAl2O3 led to the highest H2 yield but was affected by Ni leaching, whereas spinel NiAl2O4 showed a much higher stability. Therefore, the Ni-spinel catalyst showed a good potential for H2 production by APR of bio-oil aqueous fraction.

Steam Reforming of Model Bio-Oil Aqueous Fraction Using Ni-(Cu, Co, Cr)/SBA-15 Catalysts.

Hydrogen obtained from biomass derivatives is considered a promising alternative to fossil fuels. The aim of this work is to test the viability of Ni-M/SBA-15 (M: Co, Cu, Cr) catalysts for the hydrogen production from bio-oil aqueous fraction reforming. Tests were performed in a fixed-bed reactor at 600 °C and atmospheric pressure. Firstly, the steam reforming (SR) of acetic acid, hydroxyacetone, furfural and phenol, as representative constituents of the bio-oil aqueous fraction, was carried out. Lower reactivity with increasing carbon number and decreasing steam-to-carbon ratio was observed. Coking rate during SR is a consequence of carbon number and aromaticity of the reactant, as well as the steam-to-carbon ratio. However, deactivation also depends on the graphitization degree of carbon filaments, higher in the case of coke formed from phenol. Then, the performance of the Ni-M/SBA-15 catalysts was studied in the reforming of a bio-oil aqueous fraction surrogate containing the four model compounds. Ni-Co/SBA-15 and Ni-Cr/SBA-15 samples were the most active because Co also catalyze the steam reforming reactions and Cr promotes the formation of very small Ni crystallites accounting for high conversion and the low coke deposition (~8 times lower than Ni/SBA-15) in the form of poorly condensed carbon filaments.

Synthesis of Ni/CaO-γ-Al2O3@Ru Core Shell via Micro-Emulsion Method for Bio-oil Steam Reforming of Empty Fruit Bunch

Hydrogen production from bio-oil steam reforming plays an important role in the development of renewable hydrogen from biomass to produce the cleanest fuel. However, the existence of coke and low carbon conversion are problems that have been found in some studies. The purpose of this study was to reduce coke formation and to enhance carbon conversion by using core shell nanoparticle catalysts that could increase of surface area, support interaction and its catalytic activity for hydrogen production from bio-oil steam reforming of empty fruit bunch (EFB). Ni/CaO-γ-Al2O3@Ru core shells were prepared by CTAB/n-hexanol/n-hexane/water micro-emulsion system. The catalysts were characterized by means XRD, BET, FESEM-EDS and TEM. Bio-oil aqueous fraction was analyzed by using GC-MS. Carbon conversion and hydrogen yield by using Ni/CaO-γ-Al2O3@Ru core shell are resulted more 68.4 % and 18.6% than using Ni/CaO-γ-Al2O3 catalyst, respectively. The highest hydrogen yield by using Ni/CaO-γ-Al2O3@Ru core shell for steam reforming bio-oil is 5.6% in minute 10 with 0.07 g of coke deposit. The study concludes that the effect of Ni/CaO-γ-Al2O3@Ru core shell is more efficient in hydrogen production, carbon conversion and coke deposit compared to Ni/CaO-γ-Al2O3 catalyst

Production of Glucose from the Acid Hydrolysis of Anhydrosugars

Two anhydrosugar model compounds (cellobiose and levoglucosan) and a mixture of anhydrosugars from the fast pyrolysis of birch wood were subjected to acid hydrolysis using sulfuric acid as a catalyst. The anhydrosugar mixture or bio-oil aqueous fraction was found to contain mainly levoglucosan with a concentration of 30 g L–1. Hydrolysis temperature, reaction time, and catalyst to substrate molar ratios (c/s) were varied to identify their influence for glucose production. At 120 °C, 60 min, and a 0.9 c/s ratio, glucose yields of 98.55% and 96.56%, and substrate conversions of 100% and ∼92%, were achieved when hydrolyzing cellobiose and levoglucosan, respectively. An increase in the temperature to 135 °C resulted in a decrease in both glucose yield and selectivity, whereas substrate conversions around 90% were maintained for both anhydrosugars. During the hydrolysis of the bio-oil fraction, a range of conditions to achieve glucose yields above 90% was depicted. It was found that c/s ratios between 0.17 and 0.90 and temperatures between 118 and 126 °C were suitable to achieve glucose yields around 100% (30 g L–1). Furthermore, glucose concentrations of ∼117% (35 g L–1) and levoglucosan conversions above 90% were attained at 135 °C, 20 min, and a 0.2 estimated c/s ratio.

Hydrogen production by steam reforming of bio-oil aqueous fraction over Co-Fe/ZSM-5

A series of Co-Fe/ZSM-5 catalysts were prepared by impregnation method and their catalytic performance under steam reforming bio-oil aqueous fraction (SRBAF). The as-prepared catalysts were characterized by XRD, BET, and SEM. The characterization results revealed the Co-Fe alloy phase was formed in Co0.5Fe0.5/ZSM-5 catalyst, and this catalyst exhibited unique pore volume (0.28 cm3/g) and pore size (8.4 nm). The results of experiment demonstrated the addition of Fe species could significantly increase C conversion and H2 yield, and the formation of Co-Fe alloy effectively inhibited methanation reaction and improved water-gas shift (WGS) reaction. The highest H2 yield (81%) and C conversion (85%) was obtained at the following reaction conditions: 2.5 g of C0.5F0.5/Z catalyst, T = 700 °C, S/C = 10-14,.feed flow rate was 10.0 gbio-oil/h, N2 flow rate was 0.16 L/min.

Steam Reforming of Acetic Acid over Co-Supported Catalysts: Coupling Ketonization for Greater Stability

We report on the markedly improved stability of a novel 2-bed catalytic system, as compared to that of a conventional 1-bed steam reforming catalyst, for the production of H2 from acetic acid. The 2-bed catalytic system consists of (i) a basic oxide ketonization catalyst for the conversion of acetic acid to acetone, and (ii) a Co-based steam reforming catalyst, both catalytic beds placed in sequence within the same unit operation. Steam reforming catalysts are particularly prone to catalytic deactivation when steam reforming acetic acid, used here as a model compound for the aqueous fraction of bio-oil. Catalysts consisting of MgAl2O4, ZnO, CeO2, and activated carbon (AC) both with and without Co-addition were evaluated for conversion of acetic acid, and its ketonization product, acetone, in the presence of steam. It was found that over the bare oxide support only ketonization activity was observed, and coke deposition was minimal. With addition of Co to the oxide support steam reforming activity was faci...