Hydropyrolysis Of Biomass Research Articles

Experimental study and correlation analysis for the effect of hydrogen pressure on biomass fluidized hydropyrolysis under N2-H2 mixed atmosphere

The utilization of fluidized bed reactors for the biomass hydropyrolysis vapor upgrading is essential in the conversion of biomass into liquid fuels. Conducting pyrolysis experiments in fluidized bed reactors with a N2-H2 mixed atmosphere is advantageous for system operation as it allows for lower minimum operating velocities, enhances pyrolysis efficiency, and reduces heat loss. This research examines the impact of hydrogen pressure in a bubbling fluidized bed reactor using a N2-H2 mixed carrier gas, with poplar wood as the feedstock and Ni-Moγ/Al2O3 as the catalyst. Through experimental and correlation analyses, significant relationships are observed between hydrogen pressure and the production of liquid and gas-phase products, with varying effects attributed to changes in hydrogen ratio and reaction pressure. Elevated hydrogen ratios facilitate secondary reactions such as the CO2 hydrogenation, resulting in a decline in CO2 production and an elevation in the yields of light hydrocarbons and aqueous phase products. Augmenting the reaction pressure to enhance hydrogen pressure aids in promoting hydrogen saturation and cracking, and amplifying the hydrogen pressure through an increase in the reaction pressure at a specific hydrogen ratio proves more efficacious in enhancing both the quantity and quality of bio-oil produced. In the context of poplar hydropyrolysis vapor upgrading utilizing a Ni-Moγ/Al2O3 catalyst, a hydrogen ratio of 50 % at a reaction pressure of 1.5 MPa emerged as the preferred option for achieving a 12 % bio-oil yield with a moderate average bio-oil carbon number and satisfactory hydrogenation levels. This comprehensive investigation examines the influence of hydrogen pressure on biomass hydropyrolysis, highlighting variations in the impacts of changes in hydrogen ratio and reaction pressure on pyrolysis results. These results offer a theoretical framework for discerning distinctions between hydropyrolysis investigations carried out in pure hydrogen atmospheres versus mixed N2-H2 atmospheres.

Customized Atmospheric Catalytic Hydropyrolysis of Biomass to High-Quality Bio-Oil Suitable for Coprocessing in Refining Units

Customized Atmospheric Catalytic Hydropyrolysis of Biomass to High-Quality Bio-Oil Suitable for Coprocessing in Refining Units

Catalytic hydropyrolysis of biomass using natural zeolite-based catalysts

Natural clinoptilolite (coded as Escott), synthetic BEA, and mixed Escott-BEA zeolites supported nickel and iron catalysts were employed for catalytic hydropyrolysis of eucalyptus globulus leaves. Comparing non-catalytic pyrolysis and catalytic pyrolysis in N2, the use of catalysts along with H2 (30 bar) resulted in improved yields of liquid oil and gas products, with reduced production of biochar/coke. Moreover, the biochar from catalytic hydropyrolysis showed a higher mesopore surface area (97 m2/g) than non-catalytic biochar (74 m2/g). Incorporating a small amount of BEA into Escott weakens the metal-support interaction, enhances H2 adsorption activity and increases the catalyst acidity, leading to an improved aromatic monomers selectivity while preventing excessive cracking of liquid oil. Consequently, Ni-Fe/Escott-BEA catalyst shows the highest content of valuable liquid organic components. Ni-Fe/Escott, with the largest Ni particles and lowest acidity, exhibits higher selectivity to methane and naphthalenes products. In contrast, Ni-Fe/BEA with excessive acid sites exhibited significantly lower content of liquid organic products but higher yields of C2-C5 gas products and deposited carbon, primarily ascribed to its high acidity promoting coupling, cracking and deoxygenation reactions. The deactivation of Brønsted acid sites was more pronounced than Lewis acid sites, underscoring their crucial role in coupling reactions and leading to increased coke deposition.

Catalytic hydropyrolysis of biomass over NiMo bimetallic carbon-based catalysts

Catalytic hydropyrolysis (CHP) is an emerging and promising technology to convert lignocellulosic biomass resources into alternative fuels and valuable chemicals. In this work, NiMo bimetallic carbon-based catalysts were designed and applied in the thermal conversion of alkaline lignin at 450 °C, 500 °C, and 550 °C under 1 atm H2. The CHP process exhibited a higher deoxygenation extent of around 60% compared with pyrolysis (FP) and hydropyrolysis (HP) processes. The bio-oil with higher H/C ratio and lower O/C ratio corresponding to a chemical formula of CH1.167O0.245 was obtained at 500 °C over the IW catalyst prepared via incipient wetness impregnation. CO2 and CO were generated via the decarboxylation and decarbonylation reactions, respectively. As for the CHP of real biomass, the deoxygenation extent reached about 55% over different modified catalysts. The ball milling-melting catalyst showed a considerable liquid product yield of 35.0 wt% and the best bio-oil quality with the chemical formula of CH1.456O0.339. The remarkable hydrodeoxygenation activity of carbon-derived catalysts was attributed to the synergistic effect of metallic Ni0 and intermediate oxidation state of Mo2+/Moδ+. The active hydrogen was adsorbed on the nickel sites, and the molybdenum species were responsible for eliminating the oxygen in aromatic oxygenates.

Study on the reaction mechanism of C8+ aliphatic hydrocarbons obtained directly from biomass by hydropyrolysis vapor upgrading

Aviation fuel production is an important direction for biomass utilization, however, the direct transformation of biomass into aviation fuel is a bottleneck in this field. Among all the biomass-to-liquid thermochemical routes, the pyrolysis process can directly produce bio-oil in a continuous industrial manner. Herein, Ni-Mo/γ-Al2O3 catalyst was used to investigate the hydropyrolysis (HP) vapor upgrading (VU) process of lignocellulosic biomass to obtain bio-oil with high selectivity of aviation fuel components. The VU temperature of 300–350℃ was conducive to generating liquid fuel with C8+ aliphatics as the main component of jet fuel. It was indicated that the yield of the oil phase was 6.4 wt% with an HHV of 46.2 MJ/kg, while the selectivity of aliphatics reached 72.6% with C8+ aliphatics was 59.9%. Moreover, it was found that all three components of biomass could be transformed into long-chain aliphatics by coupling reaction. The hydroxyalkylation is the main way and the aldehyde group is the directing group of the carbon-increasing, which was supported by the results of the quantum chemical calculation. Further, the reaction network for the HP-VU process of lignocellulosic biomass with C8+ aliphatics as the main product was proposed to provide a theoretical understanding of the carbon-increasing in biomass hydropyrolysis.

Encapsulation Ni in HZSM-5 for catalytic hydropyrolysis of biomass to light aromatics

Ni-encapsulated (Ni@HZ5) and Ni-incorporated (xNi/HZ5) zeolites were prepared via one-pot hydrothermal synthesis and impregnation method, respectively, and further employed for hydroconversion of pyrolytic volatiles of spent coffee grounds into benzene, toluene, ethylbenzene, xylene, naphthalene (BTEXN) in a drop tube reactor under H2 atmosphere. The properties of metallic Ni species on Ni@HZ5, xNi/HZ5 and Ni/Al2O3 were comparably characterized. Ni@HZ5 displayed superior selectivity for BTEXN production among those catalysts, especially for B and T. Metallic Ni species encapsulated MFI-type framework plays crucial roles in enhancing aromatics selectivity, promoting oligomerization, cyclization and aromatization of small molecular hydrocarbons in channels. On the contrary, Ni species presented on the external zeolite surface is in favor of hydrocracking and hydrogenolysis of macromolecular pyrolytic fragments. It also exhibited high coke content containing “soft” and “hard” coke, which was mainly caused by metallic particles sintering. An important difference was proposed in the effect of Ni species on reaction pathway for catalytic upgrading of volatiles to BTEXN. The configured Ni@HZ5 inhibits sintering and has potential of enhancing BTEXN by catalytic hydropyrolysis of biomass.

Parametric effect of biomass partial hydropyrolysis process in a downer reactor to co-produce high-quality tar and syngas

Fast partial hydropyrolysis of biomass was carried out at the level with hydrogen concentration of 0% to 30% and temperatures ranging from 700 to 900 °C by using a downer pyrolyzer. A theoretical parametric effect on yields and properties of the hydropyrolysis products were clarified. It was found that the volatile matter evolved during pyrolysis was substantially increased in the presence of hydrogen. The yields of CH4, C2H6 and light tar increased with increasing elevated H2 ratio, CH4 showed an especially large yield increase. The produced methane mainly comes from the reactions of hydropyrolysis of biomass and secondary hydrogenation of tar. Moreover, the presence of alkali and alkaline earth metals matters was significant catalyzes on both reactions. The CH4 yield increased with elevating the operating temperature and optimal sweeping-gas flow rate is 150 mL/min. These results will be strengthening regulation of feedstocks-operating-products in the practical Biomass Fast Partial Hydropyrolysis technology.

The Effect of Ni-ZSM-5 Catalysts on Catalytic Pyrolysis and Hydro-Pyrolysis of Biomass.

With the demand of energy and re-utilization of wastes, the renewable lignocellulosic biomass, has attracted increasing and significant attention for alleviating the growing energy crisis and environment problems. As main components of lignocellulosic biomass, lignin, cellulose, and hemicellulose are connected by hydrogen bond to form a compact skeleton structure, resulting the trenchant condition of biomass pyrolysis. Also, pyrolysis products of above three main constituents contain a large amount of oxygenates that cause low heating value, high corrosiveness, high viscosity, and instability. Meanwhile, zeolites are of considerable significance to the conversion of lignocellulosic biomass to desirable chemical products on account of fine shape selectivity and moderate acid sites and strength. Among numerous zeolites, ZSM-5-based catalysts have been most extensively studied, and the acidity and porosity of ZSM-5 can be tuned by changing the content of Si or Al in zeolite. Beyond that, doping of other metal elements, such as Mn, Co, Ni, Ga, Ce, Pt, into ZSM-5 is also an efficient way to regulate the strength and density of acid sites in zeolite precisely. This review focused on the recent investigation of Ni-modified microporous ZSM-5 used in catalytic pyrolysis of lignin and cellulose. The application of metal-modified hierarchical ZSM-5 is also covered.

Catalytic Route for the Production of Alkanes from Hydropyrolysis of Biomass

In this work, we report a catalytic route to produce liquid alkanes from hydropyrolysis of biomass. This route uses a NiMo-HZSM-5 catalyst in-situ, and takes place primarily in three steps: 1) nick...

Aromatic hydrocarbons production and synergistic effect of plastics and biomass via one-pot catalytic co-hydropyrolysis on HZSM-5

The catalytic co-hydropyrolysis of pine sawdust (PW) and high density polyethylene (HDPE) to selectively produce aromatic hydrocarbons was studied by optimizing reaction parameters (feedstock composition, reaction temperature, residue time, initial hydrogen pressure and catalyst to reactant ratio). The composition of feedstocks, reaction temperature and the ratio of catalyst to reactant all had significant effects on the content of aromatic hydrocarbons, and the appropriate reaction parameters were selected to maximize the yield of aromatic hydrocarbons. The maximum aromatic hydrocarbons yield (18.3 %) and the highest selectively (67.8 %) were obtained when the ratio of plastic to reactant was 0.6, 400 °C, 1.5 MPa for 1 h and the catalyst to reactant ratio was 0.2. Compared with hydropyrolysis of biomass, the addition of plastics reduced the yield of solid residue and the oxygen content in bio-oil. Characteristic analysis of bio-oil showed that that monocyclic aromatic hydrocarbons accounted for the majority of aromatic hydrocarbons in blends, with benzene, toluene, xylene (BTX) having the highest selectivity (51.6–70.6 %), and oxygenates were almost absent in bio-oil. Meanwhile, the possible reaction pathways in the co-hydropyrolysis of biomass and plastic for aromatic hydrocarbons were discussed extensively.

Evaluation of pressure and temperature effects on hydropyrolysis of pine sawdust: pyrolysate composition and kinetics studies

Kinetics and product distribution from high pressure hydropyrolysis of biomass using Py-GC/MS and Py-FTIR.

Catalytic hydropyrolysis of biomass using supported CoMo catalysts – Effect of metal loading and support acidity

Catalytic hydropyrolysis of biomass to green fuels was performed using supported, sulfided CoMo catalysts. With MgAl2O4 as support material the CoMo loading was varied between 4.1 and 12.0 wt% at constant Co/Mo atomic ratio of 0.3. Increasing the metal loading decreased the amount of oxygen in the condensed organic phase from 9.0 to 4.7 wt% on dry basis (db) and the condensable organic yield decreased from 25.2 to 22.7 wt% on dry ash free (daf) basis, corresponding to a decrease in the carbon recovery from 39 to 37%. Using zeolite H-ZSM-5 mixed with alumina as support with a CoMo loading of 4.1 wt%, the condensed organics contained only 5.2 to 6.1 wt% db oxygen. The condensable organic yield was between 23.9 and 24.4 wt% db, and the carbon recovery was 39–40%. Thus using an acidic support can remove the oxygen without decreasing the carbon recovery. The latter was ascribed to alkylation of the aromatics when the zeolite support was used.Elemental maps of the spent catalysts were obtained using STEM-EDS, showing that the CoMo phase was mainly located as monolayer MoS2 slab structures (>93%) on the support and indicated a high dispersion of cobalt, consistent with incorporation of Co into the MoS2 structure in the CoMoS phase. Potassium was observed on all the spent catalysts, indicating transfer of alkali metal from the biomass to the catalyst. Potassium may decrease the acidity of the catalyst over time, thus reducing the positive effect of using a more acidic support.

Comparative study of fast pyrolysis, hydropyrolysis and catalytic hydropyrolysis of poplar sawdust and rice husk in a modified Py-GC/MS microreactor system: Insights into product distribution, quantum description and reaction mechanism

Fast pyrolysis, hydropyrolysis and catalytic hydropyrolysis are three important methods to produce bio-oil from biomass and are of great interest to researchers. In this research, the comprehensive study of pyrolysis, hydropyrolysis and catalytic hydropyrolysis of poplar sawdust and rice husk was investigated in a modified laboratory Py-GC/MS microreactor system. Rh/ZrO2 (0.5 wt %) was prepared and applied in the catalytic hydropyrolysis process. An evaluation system including estimating method of product selectivity, the calculation method of O/C and H/C ratio, deoxygenation extent (DE) and hydrogen-loss extent (HLE), was established to fully measure the deoxygenation effect. The Rh/ZrO2-assisted catalytic hydropyrolysis showed a good deoxygenation effect as O/C ratios (0.10 for poplar sawdust, 0.11 for rice husk, respectively) are comparable to that of the reported upgraded bio-oil by hydrodeoxygenation (HDO). The highest hydrocarbon selectivity of 49.14% and DE of 87.6% were obtained in catalytic hydropyrolysis of poplar sawdust. For rice husk, the hydropyrolysis process gained a similar DE (82.7%) to that of the catalytic HyPy (83.7%), because rice husk with high ash content (19.4 wt %) contains a large number of mineral elements that are likely to form a self-catalysis effect. The reaction mechanism was further inferred according to product distribution and quantum calculation of oxygen-containing products, suggesting that Rh/ZrO2-assisted hydropyrolysis was accomplished by multistage reactions, involving initial pyrolysis of raw biomass and further deoxygenation of the pyrolysis intermediates. Moreover, this work can also provide a proven methodology and theoretical supports for future studies on catalytic hydropyrolysis of biomass.

Deactivation of a CoMo Catalyst during Catalytic Hydropyrolysis of Biomass. Part 1. Product Distribution and Composition

Deactivation of a sulfided CoMo/MgAl2O4 catalyst during fluid bed catalytic hydropyrolysis of biomass (beech wood) was studied. The stability of the catalyst was investigated by converting approximately 4.4 kg of biomass and collecting the liquid and solid products for every 1 kg fed, using the same catalyst load. The total time on stream was 16.2 h. A secondary hydrotreating reactor with a sulfided NiMo/Al2O3 catalyst was used after the fluid bed to further deoxygenate the vapors. The condensed organics and C4+ gases yield for each 1 kg fed was 22.2 ± 1 wt %, which was variations within the experimental uncertainty. The CO and CO2 yield during the experiment increased from 14.9 to 18.2 wt % daf, while the aqueous phase yield decreased from 38.0 to 35.1 wt % daf. The change in CO, CO2, and aqueous phase yields was ascribed to a decrease in hydrodeoxygenation activity of the used catalysts. The concentration of oxygen in the condensed organic phase increased from 40 to 2832 ppm, indicating that deactivatio...

Deactivation of a CoMo Catalyst during Catalytic Hydropyrolysis of Biomass. Part 2. Characterization of the Spent Catalysts and Char

In this work sulfided CoMo/MgAl2O4 catalysts used in fluid bed catalytic hydropyrolysis for the conversion of beech wood and wheat straw to liquid fuels were thoroughly characterized by Raman spectroscopy and scanning (transmission) electron microscopy (S(T)EM) together with energy dispersive X-ray spectroscopy (EDS). Potassium and calcium were transferred from the beech wood to the catalyst, and the accumulated amounts increased proportionally with the time on stream (TOS) and reached 0.67 and 0.28 wt % after 16.2 h, respectively, when beech wood was used as biomass feedstock with a feeding rate of approximately 270 g/h (4.4 kg in total) beech wood to 50 g of catalyst. The concentration of coke on the spent catalyst also increased with TOS and was 3.7 wt % (carbon) after 3.5 h and 7.2 wt % after 16.2 h, indicating that the coking rate decreased with time on stream. However, SEM-EDS indicated that the carbon concentration increased more on the surface than in the bulk, thereby increasing the risk of pore ...

New insights into the effect of pressure on catalytic hydropyrolysis of biomass

Catalytic hydropyrolysis of beech wood has been conducted in a fluid bed reactor at 450 °C with a sulfided CoMo catalyst followed by a fixed bed hydrodeoxygenation (HDO) reactor with a sulfided NiMo catalyst at hydrogen pressures between 3.0 and 35.8 bar. Using both reactors the condensable organic yield (condensed organic and C4+ in gas) varied between 18.7 and 21.5 wt% dry ash free basis (daf) and was independent of the hydrogen pressure. At 15.9 bar hydrogen or higher the condensed organic phase was essentially oxygen free (<0.01 wt% dry basis (db)), but decreasing the hydrogen pressure to 3.0 bar increased the oxygen content to 7.8 wt% db. The char and coke yield was close to constant (11.0–12.7 wt% daf) at hydrogen pressures between 15.9 and 35.8 bar, but increased to 15.7 wt% at 3.0 bar hydrogen due to an increase in the polymerization of pyrolysis vapors. The measured carbon content on the spent catalysts from both the fluid bed and HDO reactor showed that coking of the catalysts increased when the hydrogen pressure was decreased below 15.9 bar. The increased coking at low hydrogen pressure (<15.9 bar) was ascribed to the polymerization of the more reactive oxygenates produced in the fluid bed reactor.

Catalytic Hydropyrolysis of Biomass Using Molybdenum Sulfide Based Catalyst. Effect of Promoters

Catalytic hydropyrolysis of beech wood was conducted in a fluid bed reactor at 450 °C and a total pressure of 26 bar. The differences in hydrodeoxygenation activity, selectivity, and the resulting ...

Selective production of aromatic hydrocarbons from lignocellulosic biomass via catalytic fast-hydropyrolysis using W2C/γ-Al2O3

This study is focused on fast hydropyrolysis of biomass followed by upgradation of pyrolysates over γ-alumina-supported tungsten carbide catalyst (W2C/γ-Al2O3). The catalyst was prepared by wet-impregnation followed by carburization, and was characterized by various techniques. Catalytic fast-hydropyrolysis experiments were performed at 500 °C in an analytical pyrolyzer coupled with gas chromatograph-mass spectrometer using pine-wood, cellulose and lignin as the feedstocks. W2C/γ-Al2O3 is proved to be an efficient hydrodeoxygenation catalyst producing aromatic and aliphatic hydrocarbons at 82% and 15% selectivities, respectively. Further, the activity of W2C/γ-Al2O3 catalyst is better than γ-Al2O3 and WO3/γ-Al2O3 in terms of both hydrocarbon selectivity and biomass conversion.

Two-stage catalytic fast hydropyrolysis of biomass for the production of drop-in biofuel

The major obstacles for the production of drop-in fuel from traditional fast pyrolysis are low bio-oil yield, poor fuel heating value and high solid yield. To overcome these obstacles, we studied the introduction of high pressure hydrogen into the pyrolysis reactor, in a process known as catalytic fast hydropyrolysis (CFHP). CFHP of anisole, a bio-oil model compound, was performed at different temperatures and pressures, to determine the effects of those variables on the CFHP reaction network. Alkanes were observed at low temperature and high pressure, whereas aromatics were dominant at low pressure and high temperature. Aspen modelling and calculation of reaction equilibrium constants showed that there is a thermodynamic barrier for simultaneous pyrolysis and hydrogenation at 600 °C. Reduced heating rates and CFHP followed by second-stage hydroprocessing (SH) were proposed as a means to control reaction temperature and efficiently deoxygenate CFHP vapors. The two-stage CFHP followed by hydroprocessing produced nearly 18 mol% carbon yield to alkanes, and a total bio-oil carbon yield of 25 mol%. The approximate bio-oil higher heating value (HHV) and aromaticity were 43.4 MJ/kg and 28 wt%, respectively, both within the range of gasoline.

Hydro-pyrolysis of lignocellulosic biomass over alumina supported Platinum, Mo2C and WC catalysts

In-line hydro-treatment of bio-oil vapor from fast pyrolysis of lignocellulosic biomass (hydro-pyrolysis of biomass) is studied as a method of upgrading the liquefied bio-oil for a possible precursor to green fuels. The nobel metal (Pt) and non-noble metal catalysts (Mo2C and WC) were compared at 500 °C and atmospheric pressure which are same as the reaction conditions for fast pyrolysis of biomass. Results indicated that under the pyrolysis conditions, the major components, such as acids and carbonyls, of the fast pyrolysis bio-oil can be completely and partially hydrogenated to form hydrocarbons, an ideal fossil fuel blend, in the hydro-treated bio-oil. The carbide catalysts perform equally well as the Pt catalyst regarding to the aliphatic and aromatic hydrocarbon formation (ca. 60%), showing the feasibility of using the cheap non-noble catalysts for hydro-pyrolysis of biomass.