Premium quality fuels and chemicals from the fluidised bed pyrolysis of biomass with zeolite catalyst upgrading

Biomass in the form of pine wood was pyrolysed in an externally heated fluidised bed pyrolysis reactor with nitrogen as the fluidising gas. A section of the freeboard of the reactor was packed with zeolite ZSM-5 catalyst. The pyrolysis oils before and after catalysis were collected in a series of condensers and cold traps. In addition, gases were analysed off-line by packed column gas chromatography. The composition of the oils and gases were determined before and after catalysis in relation to process conditions. The oils were analysed by liquid chromatography followed by gas chromatography/mass spectrometry. The results showed that the oils before catalysis were highly oxygenated, after catalysis the oils were markedly reduced in oxygenated species with an increase in aromatic species, producing a premium grade gasoline type fuel. The gases were CO₂, CO, H₂, CH₄, C₂H₄ and C₃H₆ and minor concentrations of other hydrocarbon gases. After catalysis the concentration of CO₂ and CO were increased. Detailed analysis of the upgraded oils showed that there were high concentrations of economically valuable chemicals. However, biologically active polycyclic aromatic species were also present in the catalysed oil, which increased with increasing catalyst temperature.     

Enhanced activity of NiZrBEA catalyst for upgrading of biomass pyrolysis vapors to H2-rich gas

The main objective of these studies was development of competitive catalyst for the upgrading of biomass pyrolysis vapors to H₂-rich gas. The performed experiments were devoted to determination of the effect of incorporation of zirconium into the structure of BEA zeolite on the performance of NiBEA in the mentioned process. Moreover, the most important parameters responsible for the increased activity of NiZrBEA catalyst in comparison to nickel supported on parent zeolite have been identified. The activity of synthesized catalysts was tested in two step fixed bed quartz reactor. Firstly, cellulose or pine were heated to the 500 °C in order to decompose lignocellulosic feedstock. Then, formed pyrolysis vapors were directed through catalyst bed (700 °C) where their upgrading took place. The obtained results revealed that an introduction of zirconium in the structure of BEA zeolite allowed for the increase in the efficiency of Ni catalyst in the formation of H₂-rich gas. It was related to the increase in pore volume of the synthesized materials, formation of smaller nickel oxide crystallites and creation of the catalysts with moderate acidity.     

An integrated process for biomass pyrolysis oil upgrading: A synergistic approach

Biomass pyrolysis is a promising path toward renewable liquid fuels. However, the calorific value of the pyrolysis oil (PO), also known as bio-oil, is low due to the high content of organic oxygenates and water. The oxygen content of PO can be reduced by hydrodeoxygenation, in which hydrogen is used to remove oxygen. An economic disadvantage of hydrodeoxygenation pathway is its dependence on hydrogen as an expensive feedstock. An alternative technology is to upgrade PO in hot, high pressure water, known as hydrothermal processing. The present paper studies upgrading pyrolysis oil derived from Norwegian spruce by (1) hydrodeoxygenation in a liquid hydrocarbon solvent using nanodispersed sulphide catalysts and (2) hydrothermal treatment in near-supercritical water. Experimental results and simulation studies suggested that if water soluble products are reformed for hydrogen production, the hydrodeoxygenation pathway would be a net consumer of hydrogen, whilst the hydrothermal pathway could produce a significant hydrogen excess. By comparison, the fuel yield from hydrodeoxygenation was significantly higher than hydrothermally treated fuel. Therefore, in the present study, an integrated model was proposed which demonstrates that the synergistic integration of hydrothermal and hydrodeoxygenation upgrading technologies can yield an optimal configuration which maximises fuel production, whilst obviating the need to purchase hydrogen. In this optimal configuration, 32% of raw pyrolysis-oil is hydrothermally treated and the rest is sent for hydrodeoxygenation. The results of a techno-economic analysis suggests that if the proposed integrated approach is used, it is possible to produce biofuel (43% gasoline, and 57% diesel) at a very competitive minimum selling price of 428 $ m⁻³ (1.62 $/gallon).     

Two-step steam pyrolysis of biomass for hydrogen production

In this study, different char based catalysts were evaluated in order to increase hydrogen production from the steam pyrolysis of olive pomace in two stage fixed bed reactor system. Biomass char, nickel loaded biomass char, coal char and nickel or iron loaded coal chars were used as catalyst. Acid washed biomass char was also tested to investigate the effect of inorganics in char on catalytic activity for hydrogen production. Catalysts were characterized by using Brunauer–Emmet–Teller (BET) method, X-ray diffraction (XRD) analyzer, X-ray fluorescence (XRF) and thermogravimetric analyzer (TGA). The results showed that the steam in absence of catalyst had no influence on hydrogen production. Increase in catalytic bed temperature (from 500 °C to 700 °C) enhanced hydrogen production in presence of Ni-impregnated and non-impregnated biomass char. Inherent inorganic content of char had great effect on hydrogen production. Ni based biomass char exhibited the highest catalytic activity in terms of hydrogen production. Besides, Ni and Fe based coal char had catalytic activity on H₂ production. On the other hand, the results showed that biomass char was not thermally stable under steam pyrolysis conditions. Weight loss of catalyst during steam pyrolysis could be attributed to steam gasification of biomass char itself. In contrast, properties of coal char based catalysts after steam pyrolysis process remained nearly unchanged, leading to better thermal stability than biomass char.     

Predictions of concentration in the pyrolysis of biomass materials—I

The present work involves the prediction of the concentration profiles in the case of pyrolysis of different lignocellulosic materials in isothermal and non-isothermal conditions. The operative temperature range is from 573 to 973 K for isothermal conditions, and for non-isothermal conditions, the heating rate ranges from 5 to 80 K/min (5, 20, 40, 60 and 80 K/min).

The concentration for the above mentioned conditions is predicted for various biomass components, viz. cellulose, hemicellulose and lignin. Based on the concentration profiles of different biomass materials, it is possible to predict the pyrolysis behavior over a wide range of temperatures under isothermal and non-isothermal conditions for a large number of biomass materials, provided the activation energy and the frequency factor for the various reaction steps are known. It is also possible to ascertain the degree of combustibility of different biomass materials.

The simulation model utilizes a 4th order Runge-Kutta Predictor-Corrector method to solve the coupled ordinary differential equations. Based on thermogravimetric analysis done elsewhere, it is considered that temperature and time have a linear relationship. The above technique enables us to predict concentration profiles of different biomass materials for the entire range of pyrolysis. The concentration vs time data is plotted graphically for both isothermal and non-isothermal conditions utilizing the Harvard Graphics package on a PC-A/T personal computer.     

Synergistic effect of curcumin and activated carbon catalyst enhancing hydrogen production from biomass pyrolysis

This study observes the synergistic effect of low cost and environmentally friendly catalysts, Activated Carbon and curcumin on the production of hydrogen gas in the biomass pyrolysis process. The Study used turmeric containing curcumin as an anti-oxidant agent added to the activated carbon (AC) catalyst. Biomass from coconut wood was pyrolyzed up to 550 °C using a fixed bed reactor. Both AC and curcumin were combined with a ratio of 1:0, 1:1, 1: 3, 0:1, and 3:1. The addition of AC and curcumin was able to increase the production of hydrogen and methane gas. The combination of AC and curcumin with 1:1 ratio was able to increase hydrogen gas by 25.6%. In addition, this combination was also increase methane gas by 71.8%.Curcumin as an anti-oxidant is able to prevents recombination reactions between radical molecules. Activated carbon surface is more protected from free radicals attacking and sticking to the surface. The phi-phi interaction between the two aromatic rings and the surface of activated carbon produces electrostatic forces on the surface of activated carbon to become stronger therefore it is more reactive in cracking hydrocarbon molecules and producing hydrogen gas. Software simulation, SEM, XRD, and FTIR tests were performed to support the analysis of experimental results.     

Preparation of bio-oil derived from catalytic upgrading of biomass vacuum pyrolysis vapor over metal-loaded HZSM-5 zeolites

The Fe-, Co-, Cu-loaded HZSM-5 zeolites were prepared via impregnation method. The upgrading by catalyst on biomass pyrolysis vapors was conducted over modified zeolites to investigate their catalytic upgrading performance and anti-coking performance. The Brønsted acid sites amount on Cu-,Co-loaded HZSM-5 decreased sharply, while that of Lewis both increased. The yield of liquid fraction and refined bio-oil over metal loaded ZSM-5 catalysts decreased, while that of char almost kept constant. The physical property of refined bio-oil was promoted in terms of pH value, dynamic viscosity and higher heating value (HHV). FT-IR analysis revealed that the chemical structure of refined bio-oil obtained over Fe-, Co-, Cu-loaded HZSM-5 zeolites was highly similar. The yield of monocyclic aromatic and aliphatic hydrocarbon over Fe-,Co-loaded HZSM-5 were boosted by around 2.5 times compared with original ZSM-5 zeolites. Data analysis revealed that Cu/HZSM-5 presented the worst deoxygenation ability. The anti-coking capability of Fe/HZSM-5 was obviously better, i.e., the coke content showed an approximate decrease of 38%. Thus, this study provided an efficient Fe/HZSM-5 catalysts for preparation of bio-oil derived from catalytic upgrading of biomass pyrolysis vapor.     

Hydrogen from aqueous fraction of biomass pyrolysis liquids by catalytic steam reforming in fluidized bed

Sustainable pathways for producing hydrogen as a synthesis intermediate or as a clean energetic vector will be needed in the future. Renewable biomass resources should be taken into account in this new scenario. Processing through a pyrolysis step, optimized to high liquid production (bio-oil), increases the energy bulk density of biomass for transportation. Steam reforming of the aqueous fraction is an alternative process that increases the hydrogen content of the syngas. However, the thermochemical conversion of organic compounds derived from biomass involves drawbacks such as coke formation on the catalysts. This work studies the performance of Ni-Al catalysts modified with Ca or Mg in the steam reforming of the aqueous fraction of pyrolysis liquids and the resulting coke deposits. The catalyst composition influenced the quantity and type of coke deposits. Calcium improved the formation of carbonaceous products leading to lower H₂/CO ratios while magnesium improved the WGS (water gas shift) reaction. The strategy of reducing the space velocity resulted in a low coke removal although the addition of small quantities of oxygen decreased the coke content of the catalyst by more than 50% weight. Greater efficiency and further catalyst development are needed to improve the energetic requirements of the process.     

Biocrude from biomass: pyrolysis of cottonseed cake

Fixed-bed pyrolysis experiments have been conducted on a sample of cottonseed cake to determine the possibility of being a potential source of renewable fuels and chemicals feedstocks, in two different reactors, namely a tubular and a Heinze retort. Pyrolysis atmosphere and pyrolysis temperature effects on the pyrolysis product yields and chemical composition have been investigated. The maximumm oil yield of 29.68% was obtained in N₂ atmosphere at a pyrolysis temperature of 550°C with a heating rate of 7°C min⁻¹ in a tubular reactor.     

Biochar from microwave pyrolysis of biomass: A review

Microwave based technology is an alternative heating method and has already been successfully used in biomass pyrolysis for biochar and biofuel production thanks to its fast, volumetric, selective and efficient heating. Previous review mainly focused on production and analysis of bio-oil and gas instead of biochar. The current paper provides a review of microwave-assisted pyrolysis (MWP) of biomass and its biochar characteristics, including product distribution and biochar yield, biochar properties, microwave absorbers (MWAs) and catalysts commonly used in MWP, as well as comparison of biochar derived from MWP and conventional pyrolysis (CP). MWAs not only absorb microwave energy, they also act as catalysts to interact with gas, vapor and solids in the reactor, adjusting the product distribution and quality of products. It was reported for MWP that the highest biochar yield was >60 wt% and the maximum BET surface area was about 450–800 m²/g. Technology status and economics of MWP of biomass in China were briefly introduced. The Optimization of yield and quality of biochar strongly depends on feedstock properties, reactor types, operating parameters, MWAs and catalysts added to the system.     

Utilization of NiO/porous ceramic monolithic catalyst for upgrading biomass fuel gas

Catalytic steam reforming for producing high quality syngas from biomass fuel gas was studied over monolithic NiO/porous ceramic catalysts in a fixed-bed reactor. Effects of reaction temperature, steam to carbon (S/C) ratio, and nickel loading content on catalyst performance were investigated. Results indicated that the NiO/porous ceramic monolith catalyst had a good ability to improve bio-fuel gas quality. H₂ yield, H₂ + CO content, and H₂/CO ratio in produced gas were increased when reaction temperature was increased from 550 to 700 °C. H₂ yield was increased from 28.1% to 40.2% with S/C ratio increased from 1 to 2. And the yield of hydrogen was stabilized with the further increase of S/C ratio. Catalyst activity was not always enhanced with increased nickel content, when NiO loading content reaches 5.96%, serious aggregation and sintering of active composition on catalyst surface occur. The best performance, in terms of H₂ yield, is obtained with 2.50% NiO content at reaction temperature of 700 °C and S/C ratio of 2.     

Aromatic fuel oils produced from the pyrolysis-catalysis of polyethylene plastic with metal-impregnated zeolite catalysts

Pyrolysis-catalysis of high density polyethylene (HPDE) was carried out in a fixed bed, two stage reactor for the production of upgraded aromatic pyrolysis oils. The catalysts investigated were Y-zeolite impregnated with transition metal promoters with 1 wt% and 5 wt% metal loading of Ni, Fe, Mo, Ga, Ru and Co to determine the influence on aromatic fuel composition. Pyrolysis of the HDPE took place at 600 °C in the first stage of the reactor system and the evolved pyrolysis gases were passed to the second stage catalytic reactor, which had been pre-heated to 600 °C. Loading of metals on the Y-zeolite catalyst led to a higher production of aromatic hydrocarbons in the product oil with greater concentration of single ring aromatic hydrocarbons produced. The single ring aromatic compounds consisted of mainly toluene, ethylbenzene and xylenes, while the 2-ring hydrocarbons were mainly naphthalene and their alkylated derivatives. There was a reduction in the production of multiple ring aromatic compounds such as, phenanthrene and pyrene. The addition of the promoter metals appeared to have only a small influence on aromatic oil content, but increased the hydrogen yield from the HDPE. However, there was significant carbon deposition on the catalysts in the range 14–22 wt% for the 1% metal-Y-zeolite catalysts and increased to 18–26 wt% for the 5 wt% metal-Y-zeolite catalysts.     

生物质燃料层热解过程的传热传质模型研究

通过分析生物质热解过程的传热传质特点,建立了生物质燃料层热解过程的传热传质教学模型。通过数值计算,研究了生物质燃料层在热解过程中所发生的热量和质量迁移现象,分析了热解过程生物质床内部温度场的分布、生物质固体密度的变化和热解区的迁移规律。     

Experimental study on catalytic effect of biomass pyrolysis volatile over nickel catalyst supported by waste iron slag

The study aims to analyze catalytic tar destruction, evaluate the activity of the Ni‐based catalyst supported by waste iron slag, and obtain clean pyrolysis syngas. The effects of different nickel loadings, catalytic temperatures, and catalyst calcination temperatures on volatile were investigated in order to determine the optimal process condition. The analysis results showed that the iron slag Ni‐based catalyst had a relatively low specific surface area. However, it showed an excellent resistance performance to the coke deposition and displayed the high tar removal ability. Moreover, the tar conversion and the yield of syngas were significantly affected by nickel loadings. When the nickel loading reached 3%, the tar dew point was decreased by nearly 100 °C and the tar conversion reached 94.84%. The favorable reaction temperature was about 800 °C based on the consideration of energy consumption and the catalytic performance. Calcination temperature affected tar yield and syngas yield. The application of iron slag in nickel catalyst realized the reutilization of waste materials, indicating significant practical values. Copyright © 2017 John Wiley & Sons, Ltd.     

Hydrogen synthesis from biomass pyrolysis with in situ carbon dioxide capture using calcium oxide

Hydrogen (H₂) and other gases (CO₂, CO, CH₄, H₂O) produced during the pyrolysis of cellulose, xylan, lignin and pine (Pinus radiata), with and without added calcium oxide (CaO), were studied using thermogravimetry-mass spectrometry (TG-MS) and thermodynamic modeling. CaO improved the H₂ yield from all feedstocks, and had the most significant effect on xylan. The weight loss of and gas evolution from the feedstocks were measured over the temperature range 150-950 °C in order to investigate the principle mechanism(s) of H₂ formation. Without added CaO, little H₂ was produced during primary pyrolysis; rather, most H₂ was generated from tar-cracking, reforming, and char-decomposition reactions at higher temperatures. When CaO was added, significant H₂ was produced during primary pyrolysis, as the water-gas shift reaction was driven toward H₂ formation. CaO also increased the formation of H₂ from reforming and char gasification reactions. Finally, CaO increased the extent of tar cracking and char decomposition, and lowered their onset temperatures. The production of H₂ from pine over the course of pyrolysis could be modeled by summing the H₂ evolutions from the separate biomass components in relevant proportions.     

Hydrogen production from biomass combining pyrolysis and the secondary decomposition

An efficient method of hydrogen production from biomass was studied in this paper. The pyrolysis of biomass was combined with the secondary decomposition of gaseous intermediate for hydrogen-rich gas production, with the avoidance of N₂ and CO₂ dilution to the energy density of gaseous effluents. In order to acquire the optimum conditions for hydrogen generation, effects of operating parameters on this two-step decomposition of biomass were analyzed through simulation of thermodynamic equilibrium and experiments using Ni/cordierite catalyst. The results indicate that the operating parameters, including pyrolysis temperature 923 K, 18 min of residence time, the secondary decomposition temperature 1123 K and molar steam to carbon ratio 2, satisfy all the criteria for high hydrogen content and energy efficiency. Hydrogen content of above 60% and hydrogen yield of around 65 g/kg biomass were achieved with optimized conditions. The hydrogen-rich gas is preferred for potential utilization in downstream fuel cells for the implementation of distributed energy supply, and is also practical for pure hydrogen production.     

Production of synthesis gas by partial oxidation and steam reforming of biomass pyrolysis oils

As the lowest cost biomass-derived liquids, pyrolysis oils (also called bio-oils) represent a promising vector for biomass to fuels conversion. However, bio-oils require upgrading to interface with existing infrastructure. A potential pathway for producing fuels from pyrolysis oils proceeds through gasification, the conversion to synthesis gas. In this work, the conversion of bio-oils to syngas via catalytic partial oxidation over Rh–Ce is evaluated using two reactor configurations. In one instance, pyrolysis oils are oxidized in excess steam in a freeboard and passed over the catalyst in a second zone. In the second instance, bio-oils are introduced directly to the catalyst. Coke formation is avoided in both configurations due to rapid oxidation. H₂ and CO can be produced autothermally over Rh–Ce catalysts with millisecond contact times. Co-processing of bio-oil with methane or methanol improved the reactor operation stability.     

Comparative study on pyrolysis and catalytic pyrolysis upgrading of biomass model compounds: Thermochemical behaviors,kinetics, and aromatic hydrocarbon formation

In order to understand the pyrolysis mechanism, reaction kinetic and product properties of biomass and select suitable agricultural and forestry residues for the generation desired products, the pyrolysis and catalytic pyrolysis characteristics of three main components (hemicellulose, cellulose, and lignin) of biomass were investigated using a thermogravimetric analyzer (TGA) with a fixed-bed reactor. Fourier transform infrared spectroscopy (FTIR) and elemental analysis were used for further characterization. The results showed that: the thermal stability of hemicellulose was the worst, while that of cellulose was higher with a narrow range of pyrolysis temperatures. Lignin decomposed over a wider range of temperatures and generated a higher char yield. After catalytic pyrolysis over HZSM-5 catalyst, the conversion ratio increased. The ratio for the three components was in the following order: lignincellulose < biomass < xylan. The Starink method was introduced to analyze the thermal reaction kinetics, activation energy (Ea), and the pre-exponential factor (A). The addition of HZSM-5 improved the reactivity and decreased the activation energy in the following order: xylan (30.54%) > biomass(15.41%) > lignin (14.75%) > cellulose (6.73%). The pyrolysis of cellulose gave the highest yield of bio-oil rich in levoglucosan and other anhydrosugars with minimal coke formation. Xylan gave a high gas yield and moderate yield of bio-oil rich in furfural, while lignin gave the highest solid residue and produced the lowest yield of bio-oil that was rich in phenolic compounds. After catalytic pyrolysis, xylan gave the highest yield of monocyclic aromatic hydrocarbons, 76.40%, and showed selectivity for benzene and toluene. Cellulose showed higher selectivity for xylene and naphthalene; however, lignin showed enhanced for selectivity of C10 + polycyclic aromatic hydrocarbons. Thus, catalytic pyrolysis method can effectively improve the properties of bio-oil and bio-char.     

Effect of CO2 atmosphere on biomass pyrolysis and in-line catalytic reforming

To enhance the conversion efficiency of biomass CO₂ gasification and decrease tar, the experimental study of biomass pyrolysis and in-line catalytic CO₂ reforming (BPy-ILCCR) were investigated in a two-stage reactor. The prepared K-Ni/Al catalyst exhibits superior catalytic activity for gas products in BPy-ILCCR. Results show that both CO₂ concentration and temperature promote the rise of the gas production, but the increase slows down when CO₂ concentration is more than 40 vol%. At 700°C, the gas yield and X_c can reach 0.83 g/g-bio and 92.4%, respectively (40 vol% CO₂, 3 g catalyst). The comparative study indicates that steam is slightly better for reducing liquid product under the same concentration of CO₂ and H₂O, and the X_c at 80 vol% CO₂ can reach 93.9%, close to the value obtained at 40 vol% H₂O. Moreover, there exist similar quantities of coke deposition on the catalyst under the CO₂ and H₂O atmosphere.     

Fuel conversion characteristics of black liquor and pyrolysis oil mixtures: Efficient gasification with inherent catalyst

Alkali metals inherent in black liquor (BL) have strong catalytic activity during gasification. A catalytic co-gasification process based on BL with pyrolysis oil (PO) has the potential to be a part of efficient and fuel-flexible biofuel production systems. The objective of the paper is to investigate how adding PO into BL alters fuel conversion under gasification conditions. First, the conversion times of single fuel droplet were observed in a flat flame burner under different conditions. Fuel conversion times of PO/BL mixtures were significantly lower than PO and comparable to BL. Initial droplet size (300–1500 μm) was the main variable affecting devolatilization, indicating control by external heat transfer. Char oxidation was affected by droplet size and the surrounding gas composition. Then, the intrinsic reactivity of char gasification was measured in an isothermal thermogravimetric analyser at T = 993–1133 K under the flow of CO₂–N₂ mixtures. All the BL-based samples (100% BL, 20% PO/80% BL, and 30% PO/70% BL on mass basis) showed very high char conversion. Conversion rate of char gasification for PO/BL mixtures was comparable to that of pure BL although the fraction of alkali metal in char decreased because of mixing. The reactivities of BL and BL/PO chars were higher than the literature values for solid biomass and coal chars by several orders of magnitude. The combined results suggest that fuel mixtures containing up to 30% of PO on mass basis may be feasible in existing BL gasification technology.