Hydrogen production from catalytic steam reforming of biomass pyrolysis oil or bio-oil derivatives: A review

Steam reforming of biomass pyrolysis oil or bio-oil derivatives is one of the attractive approaches for hydrogen production. The current research focused on the development of promising catalysts with favorable catalytic activity and high coke resistance. Noble metal such as Rh has been proven to achieve promising reforming reaction efficiencies. However, Ni has attracted considerable attention owing to its stability, cost effectiveness, and good activity in breaking C–C and C–H bonds. Nevertheless, Ni-based catalysts have serious carbon deposition problems arising from chemical poisoning, metal sintering, and poor metal dispersion. This paper attempted to review the current trends in catalyst development considering the aspects of supports, metals, and promoters as an effort to find possible solutions for the limitations of Ni-based catalysts. The present review also covered the current understanding on the reaction mechanisms as well as the future prospects in the field of steam reforming catalysts.     

Kinetic modeling and optimization of biomass pyrolysis for bio-oil production

Thermo-kinetic models for biomass pyrolysis were simulated under both isothermal and non-isothermal conditions to predict the optimum parameters for bio-oil production. A comparative study for wood, sewage sludge, and newspaper print pyrolysis was conducted. The models were numerically solved by using the fourth order Runge–Kutta method in Matlab-7. It was also observed that newspaper print acquired least pyrolysis time to attain optimum bio-oil yield followed by wood and sewage sludge under the identical conditions of temperature and heating rate. Thus, at 10 K/min, the optimum pyrolysis time was 21.0, 23.8, and 42.6 min for newspaper print, wood, and sewage sludge, respectively, whereas the maximum bio-oil yield predicted was 68, 52, and 36%, respectively.     

移动床内高炉渣热载体与生物质热解液化实验研究

以移动床为高炉渣余热裂解生物质实验平台,研究高炉渣温度、粒径和生物质粒径等对生物质热解产物分布的影响。结果表明,生物油产率随着高炉渣温度的增加先增加后减小,当高炉渣热载体温度为650℃时,生物油产率最高;高炉渣粒径和生物质粒径越小,生物油的产率越大。炉渣温度650℃、粒径0~2mm,生物质粒径小于75μm,生物质油产率达到57.3%。生物油中含氧量和含水率较高,热值低,pH值为3.7。     

生物质快速热解制生物油的工艺分析

文章利用Aspen Plus软件建立了一个完整的生物质快速热解制生物油的流程模型,并详细描述模型的建立过程,模型包括原料的预处理、快速热解、焦炭和不冷凝气体的燃烧3个部分。通过对日处理2 000 t玉米秸秆的快速热解制生物油工厂各工段进行模拟,结果表明,整个生产过程各种形式的能耗为468.73×109J/h,能量产出为531.6×109J/h,能量产出大于能量消耗;将能量折算成标准煤用量后可知,生产1 kg生物油的能耗相当于0.758 8 kg标准煤,同时产出的能量相当于0.860 6 kg标准煤;焦炭的燃烧量为总量的86%时,可以满足快速热解过程的能量需求。     

Optimization and characterization studies on bio-oil production from palm shell by pyrolysis using response surface methodology

In this work palm shell waste was pyrolyzed to produces bio-oil. The effects of several parameters on the pyrolysis efficiency were tested to identify the optimal bio-oil production conditions. The tested parameters include temperature, N₂ flow rate, feed-stock particle size, and reaction time. The experiments were conducted using a fix-bed reactor. The efficient response surface methodology (RSM), with a central composite design (CCD), were used for modeling and optimization the process parameters. The results showed that the second-order polynomial equation explains adequately the non-linear nature of the modeled response. An R² value of 0.9337 indicates a sufficient adjustment of the model with the experimental data. The optimal conditions found to be at the temperature of 500 °C, N₂ flow rate of 2 L/min, particle size of 2 mm and reaction time of 60 min and yield of bio-oil was approximately obtained 46.4 wt %. In addition, Fourier Transform infra-red (FT-IR) spectroscopy and gas chromatography/mass spectrometry (GC-MS) were used to characterize the gained bio-oil under the optimum condition.     

Study of bio-oil and bio-char production from algae by slow pyrolysis

This study examined bio-oil and bio-char fuel produced from Spirulina Sp. by slow pyrolysis. A thermogravimetric analyser (TGA) was used to investigate the pyrolytic characteristics and essential components of algae. It was found that the temperature for the maximum degradation, 322 °C, is lower than that of other biomass. With our fixed-bed reactor, 125 g of dried Spirulina Sp. algae was fed under a nitrogen atmosphere until the temperature reached a set temperature between 450 and 600 °C. It was found that the suitable temperature to obtain bio-char and bio-oil were at approximately 500 and 550 °C respectively. The bio-oil components were identified by a gas chromatography/mass spectrometry (GC–MS). The saturated functional carbon of the bio-oil was in a range of heavy naphtha, kerosene and diesel oil. The energy consumption ratio (ECR) of bio-oil and bio-char was calculated, and the net energy output was positive. The ECR had an average value of 0.49.     

Preparation and characterization of bio-oil by microwave pyrolysis of biomass

A low temperature method was used to produce bio-oil from fir sawdust by means of microwave pyrolysis. Effects of reaction temperature, ratios of the microwave absorption medium to sawdust, and reaction time on the yield of bio-oil were investigated. The results show that an optimized yield of 21.22% is achieved. Bio-oil obtained was analyzed by gas chromatography-mass spectrometry and Fourier transform infrared, and the result reveals that the product mainly consists of phenolic compounds with esteric compounds as the minor components. Thermal weight loss curves of bio-oil were determined by thermogravimetry-differential thermal analysis in the oxygen atmosphere at different super-heating rates, and combustion kinetic parameters were calculated.     

Hydrogen-rich gas production from a biomass pyrolysis gas by using a plasmatron

Pyrolysis and gasification is an energy conversion technology process that produces industrially useful syngas from various biomasses. However, due to the tars in the product gases generated from the pyrolysis/gasification of biomass, this process damages and causes operation problems with equipment that use product gases such as gas turbines and internal engines.     

A review on current status of hydrogen production from bio-oil

Increase in energy demand and growing environmental awareness has increased interest for alternative renewable energy sources over the last few years. Hydrogen produces only water during combustion, and therefore, it is seen as an alternative fuel for locomotive application. Nonetheless, hydrogen is not an energy source; rather it is an energy carrier. Different techniques are being explored to find an economical way of generating hydrogen from renewable resources. Hydrogen production from water using sunlight is still expensive. Biomass is another alternative to produce hydrogen. Bio-oil derived from biomass using a fast pyrolysis is a potential source for hydrogen production. Although different techniques have been employed to produce hydrogen from bio-oil, significant effort has been put into steam reforming process. This paper reviews major hydrogen production techniques with a great deal of importance given to steam reforming. The important factors that are known to affect hydrogen yield are temperature, steam to carbon ratio, and catalyst type. Literature review of bio-oil steam reforming technique has been done, and a comparison of experimental conditions has been carried out. However, as a major shortcoming, this technique is accompanied by the formation of carbonaceous deposits over the catalyst surface rendering it inactive and requiring frequent regeneration. Coke formation has been cited as the major disadvantage of bio-oil reforming, and it is more pronounced when Ni based catalysts are used.     

农林生物质热裂解制取合成气的研究

以树叶为原料，利用热裂解装置进行了试验。并对裂解产物的组成进行了分析。结果表明：树叶热裂解产物为生物油、合成气和炭，其合成气成分主要由CO、CH4、H2和水蒸气组成。     

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.     

Enhancing hydrogen production from biomass pyrolysis by dental-wastes-derived sodium zirconate

Sodium zirconate was synthesized via the solid-phase reaction from dental wastes with sodium carbonate. The dental-wastes-derived sodium zirconate (DW-SZ) dramatically enhanced hydrogen (H₂) production during biomass pyrolysis due to the presence of alkali metal (Na) and in-situ carbon dioxide (CO₂) capture. To be specific, the DW-SZ could maintain a maximum CO₂ uptake of 0.195 g-CO₂ g-sorbent⁻¹ at the 30th cycle under cyclic CO₂ absorption/desorption swings. The total CO₂ uptake in all 30 cycles reached 82% of the theoretical CO₂ uptake. The synthesized functional material was subsequently employed for H₂ production in the pyrolysis of three different biomass samples (i.e., municipal sludge, spirulina, and methylcellulose). The highest H₂ yield of 205 ml g⁻¹ was produced by spirulina in presence of functional material, followed by methylcellulose (197 ml g⁻¹), and municipal sludge (142 ml g⁻¹). Moreover, the DW-SZ was characterized by XRD, BET and SEM to help unravel and justify the underlying reaction mechanisms.     

Distributed production of hydrogen by auto-thermal reforming of fast pyrolysis bio-oil

We demonstrated an auto-thermal reforming process for producing hydrogen from biomass pyrolysis liquids. Using a noble metal catalyst (0.5% Pt/Al₂O₃ from BASF) at a methane-equivalent space velocity of around 2000 h⁻¹, a reformer temperature of 800 °C–850 °C, a steam-to-carbon ratio of 2.8–4.0, and an oxygen-to-carbon ratio of 0.9–1.1, we produced 9–11 g of hydrogen per 100 g of fast pyrolysis bio-oil, which corresponds to 70%–83% of the stoichiometric potential. The elemental composition of bio-oil and the bio-oil carbon-to-gas conversion, which ranged from 70% to 89%, had the most significant impact on the yield of hydrogen. Because of incomplete volatility the remaining 11%–30% of bio-oil carbon formed deposits in the evaporator. Assuming the same process efficiency as that in the laboratory unit, the cost of hydrogen production in a 1500 kg/day plant was estimated at $4.26/kg with the feedstock, fast pyrolysis bio-oil, contributing 56.3% of the production cost.     

Influence of reaction conditions on bio-oil production from pyrolysis of construction waste wood

The pyrolysis characteristics of construction waste wood were investigated for conversion into renewable liquid fuels. The activation energy of pyrolysis derived from thermogravimetric analysis increased gradually with temperature, from 149.41 kJ/mol to 590.22 kJ/mol, as the decomposition of cellulose and hemicellulose was completed and only lignin remained to be decomposed slowly. The yield and properties of pyrolysis oil were studied using two types of reactors, a batch reactor and a fluidized-bed reactor, for a temperature range of 400–550 °C. While both reactors revealed the maximum oil yield at 500 °C, the fluidized-bed reactor consistently gave larger and less temperature-dependent oil yields than the batch reactor. This type of reactor also reduced the moisture content of the oil and improved the oil quality by minimizing the secondary condensation and dehydration. The oil from the fluidized-bed reactor resulted in a larger phenolic content than from the batch reactor, indicating more effective decomposition of lignin. The catalytic pyrolysis over HZSM-5 in the batch reactor increased the proportion of light phenolics and aromatics, which was helpful in upgrading the oil quality.     

Multi-response optimization of bio-oil production from catalytic solar pyrolysis of Spirulina platensis

In this work, the solar catalytic pyrolysis of Spirulina platensis microalgae using hydrotalcite as a catalyst was studied to improve the yield and quality of the bio-oil obtained from the algae. The effects of biomass loading, reaction time, and catalyst percentage on the product distribution and bio-oil composition were evaluated. The desirability function was used to identify the pyrolysis conditions that maximize the bio-oil yield and its hydrocarbon content. The experimental results indicated that the catalytic pyrolysis of Spirulina platensis produced considerable solid product content, and high liquid yields were reached in some tests favored by the catalyst presence. The hydrotalcite contributed to increasing the hydrocarbon formation in the bio-oil at lower reaction times, demonstrating the great performance of this catalyst for microalgae pyrolysis. At the optimal conditions, a bio-oil yield of 35.94% with 21.71% hydrocarbon content was achieved.     

Economic tradeoff between biochar and bio-oil production via pyrolysis

This paper examines some of the economic tradeoffs in the joint production of biochar and bio-oil from cellulosic biomass. The pyrolysis process can be performed at different final temperatures, and with different heating rates. While most carbonization technologies operating at low heating rates (large biomass particles) result in higher yields of charcoal, fast pyrolysis (which processes small biomass particles) is the preferred technology to produce bio-oils. Varying operational and design parameters can change the relative quantity and quality of biochar and bio-oil produced for a given feedstock. These changes in quantity and quality of both products affect the potential revenue from their production and sale. We estimate quadratic production functions for biochar and bio-oil. The results are then used to calculate a product transformation curve that characterizes the yields of bio-oil and biochar that can be produced for a given amount of feedstock, movement along the curve corresponds to changes in temperatures, and it can be used to infer optimal pyrolysis temperature settings for a given ratio of biochar and bio-oil prices.     

Microwave-assisted catalytic pyrolysis of cellulose for phenol-rich bio-oil production

The microwave-assisted catalytic pyrolysis (MACP) of cellulose was carried out using modified HZSM-5 catalysts for bio-oil production. The catalysts of Fe/HZSM-5, Ni/HZSM-5 and Fe–Ni/HZSM-5 were developed and characterized by the X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The bio-oil was characterized by the Fourier transform infrared analyzer (FTIR) and gas chromatography/mass spectrometry (GC/MS). Results showed that Fe/HZSM-5 enhanced the yields of bio-oil by 11.4% and decreased the coke by about 24% compared to HZSM-5 without modification. The saccharides in bio-oil disappeared and were totally converted into phenols and low molecular compounds with the catalysis of Fe–Ni/HZSM-5. Fe–Ni/HZSM-5 showed high selectivity of phenols (20.86%) in the bio-oil. It was a unique finding because usually phenols can only be obtained by the pyrolysis of lignin, not cellulose. The formation of phenols from MACP of cellulose was probably caused by the conversion of furans to aromatics in the pores of HZSM-5, and followed by further conversion of aromatics into phenols on the external surface of HZSM-5.     

Lignocellulosic biomass pyrolysis mechanism: A state-of-the-art review

The past decades have seen increasing interest in developing pyrolysis pathways to produce biofuels and bio-based chemicals from lignocellulosic biomass. Pyrolysis is a key stage in other thermochemical conversion processes, such as combustion and gasification. Understanding the reaction mechanisms of biomass pyrolysis will facilitate the process optimization and reactor design of commercial-scale biorefineries. However, the multiscale complexity of the biomass structures and reactions involved in pyrolysis make it challenging to elucidate the mechanism. This article provides a broad review of the state-of-art biomass pyrolysis research. Considering the complexity of the biomass structure, the pyrolysis characteristics of its three major individual components (cellulose, hemicellulose and lignin) are discussed in detail. Recently developed experimental technologies, such as Py-GC–MS/FID, TG-MS/TG-FTIR, in situ spectroscopy, 2D-PCIS, isotopic labeling method, in situ EPR and PIMS have been employed for biomass pyrolysis research, including online monitoring of the evolution of key intermediate products and the qualitative and quantitative measurement of the pyrolysis products. Based on experimental results, many macroscopic kinetic modeling methods with comprehensive mechanism schemes, such as the distributed activation energy model (DAEM), isoconversional method, detailed lumped kinetic model, kinetic Monte Carlo model, have been developed to simulate the mass loss behavior during biomass pyrolysis and to predict the resulting product distribution. Combined with molecular simulations of the elemental reaction routes, an in-depth understanding of the biomass pyrolysis mechanism may be obtained. Aiming to further improve the quality of pyrolysis products, the effects of various catalytic methods and feedstock pretreatment technologies on the pyrolysis behavior are also reviewed. At last, a brief conclusion for the challenge and perspectives of biomass pyrolysis is provided.     

Investigation on hydrogen production by catalytic steam reforming of maize stalk fast pyrolysis bio-oil

Hydrogen production via catalytic steam reforming of maize stalk fast pyrolysis bio-oil over the nickel/alumina supported catalysts promoted with cerium was studied using a laboratory scale fixed bed coupled with Fourier transform infrared spectroscopy/thermal conductivity detection analysis (FTIR/TCD). The effects of nickel loading, reaction temperature, water to carbon molar ratio (WCMR) and bio-oil weight hourly space velocity (W_bHSV) on hydrogen production were investigated. The highest hydrogen yield of 71.4% was obtained over the 14.9%Ni-2.0%Ce/A1₂O₃ catalyst under the reforming conditions of temperature = 900 °C, WCMR = 6 and W_bHSV = 12 h⁻¹. Increasing reaction temperature from 600 to 900 °C resulted in the significant increase of hydrogen yield. The hydrogen yield was significantly enhanced by increasing the WCMR from 1 to 3, whereas it increased slightly by further increasing WCMR. The hydrogen yield decreased with the increase of W_bHSV. Meanwhile, the coke deposition percentage changed little with increasing W_bHSV up to 12 h⁻¹ and then it increased by 4.5% with the further increase of W_bHSV from 12 to 24 h⁻¹.     

Power generation using fast pyrolysis liquids from biomass

Power production from biomass derived pyrolysis liquids has been under development for the past few years. If technically successful, it would make decentralized bio-energy production possible. Several technologies and system components have been developed by academia, R&D organizations, and industrial companies in many countries. Much experience has been gained and many useful results published. The present work aims at reviewing the most significant experience in power generation from biomass liquids produced by fast pyrolysis processes. Power plant technologies addressed are diesel engines, gas turbines, and natural gas/steam power plants. Main results are reviewed and R&D needs identified for each technology. The analysis shows that even for the most promising solutions long-term demonstration has not yet been achieved. Pyrolysis liquid use in gas turbine plants and in co-firing mode in large power stations are technically most advanced. Recent work with diesel engines also appears quite promising.