Steam Reforming of Biomass Pyrolysis Oil: A Review (original) (raw)
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Catalysts
The present review focuses on the production of renewable hydrogen through the catalytic steam reforming of bio-oil, the liquid product of the fast pyrolysis of biomass. Although in theory the process is capable of producing high yields of hydrogen, in practice, certain technological issues require radical improvements before its commercialization. Herein, we illustrate the fundamental knowledge behind the technology of the steam reforming of bio-oil and critically discuss the major factors influencing the reforming process such as the feedstock composition, the reactor design, the reaction temperature and pressure, the steam to carbon ratio and the hour space velocity. We also emphasize the latest research for the best suited reforming catalysts among the specific groups of noble metal, transition metal, bimetallic and perovskite type catalysts. The effect of the catalyst preparation method and the technological obstacle of catalytic deactivation due to coke deposition, metal sinte...
International Journal of Hydrogen Energy, 2014
The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: catalytic and non-catalytic steam reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final steam reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the steam reforming experiments, catalytic and non-catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different catalytic reactors were tested in the catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H 2 yields were as follows: catalytic steam reforming of the aqueous fractions in fixed bed (0.17 g H 2 /g organics) > non-catalytic steam reforming of the bio-oils (0.14 g H 2 /g organics) > non-catalytic steam reforming of the aqueous fractions (0.13 g H 2 /g organics) > catalytic steam reforming of the aqueous fractions in fluidized bed (0.07 g H 2 /g organics). These different H 2 yields are a consequence of the different temperatures used in the reforming processes (650 C and 1400 C for the catalytic and the non-catalytic, respectively) as well as the high spatial velocity employed in the catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor.
Hydrogen from Biomass: Steam Reforming of Model Compounds of Fast-Pyrolysis Oil
Energy & Fuels, 1999
We investigated the production of hydrogen by the catalytic steam reforming of model compounds of biomass fast-pyrolysis oil (bio-oil). Acetic acid, m-cresol, dibenzyl ether, glucose, xylose, and sucrose were reformed using two commercial nickel-based catalysts for steam reforming naphtha. The experiments were conducted at a methane-equivalent gas hourly space velocity (G C1 HSV) from 500 to 11790 h-1. Steam-to-carbon ratios (S/C) of 3 and 6 and catalyst temperatures from 550 to 810°C were selected. Rapid coking of the catalyst was observed during acetic acid reforming at temperatures lower than 650°C. Acetic acid, m-cresol, and dibenzyl ether were completely converted to hydrogen and carbon oxides above this temperature, and hydrogen yields ranged from 70 to 90% of the stoichiometric potential, depending on the feedstock and reforming conditions. Sugars were difficult to reform because they readily decomposed through pyrolysis in the freeboard of the reactor. This led to the formation of char and gases before contacting the catalyst particles.
Hydrogen Production from Biomass Pyrolysis and In-line Catalytic Steam Reforming
2015
Hydrogen production from pyrolysis-catalytic steam reforming of pine sawdust has been investigated using two subsequent reactors: i) a conical spouted bed reactor for biomass pyrolysis at 500 °C, and ii) a fluidized bed reactor for catalytic reforming of volatiles from the pyrolysis step. A commercial Ni reforming catalyst has been used for the reforming step (Reformax® 330). 99.7 % conversion and a H2 yield of 93.45 % are achieved at 600 °C, 0.28 gcatalyst h gbiomass-1 and S/C ratio of 8.2, producing 11.2 g of hydrogen per 100 g of biomass fed into the process. Increasing reaction time, higher coke contents are deposited on the catalyst due to secondary reactions. This is the main cause of catalyst activity decrease, although deactivation is attenuated by the good performance of the fluidized bed reactor and the excess of steam in the reaction medium (high S/C ratio).
Catalytic Steam Reforming of Bio-Oil to Hydrogen Rich Gas
2013
Bio-oil is a liquid produced by pyrolysis of biomass and its main advantage compared with biomass is an up to ten times higher energy density. This entails lower transportation costs associated with the utilization of biomass for production of energy and fuels. Nevertheless, the bio-oil has a low heating value and high content of oxygen, which makes it unsuited for direct utilization in engines. One prospective technology for upgrading of bio-oil is steam reforming (SR), which can be used to produce H2 for upgrading of bio-oil through hydrodeoxygenation or synthesis gas for processes like the Fischer-Tropsch synthesis. In the SR of bio-oil or biooil model compounds high degrees of conversion and high yields of H2 can be achieved, but stability with time-on-stream is rarely achieved. The deactivation is mainly due to carbon deposition and is one of the major hurdles in the SR of bio-oil. There are two main pathways to minimize carbon deposition in steam reforming; either through opti...
Renewable hydrogen production from bio-oil derivative via catalytic steam reforming: An overview
Renewable and Sustainable Energy Reviews, 2017
Tremendous research efforts have been dedicated towards development and utilization of sustainable alternative energy resources. Depletion of fossil fuels and the rising environmental concerns such as global warming are among the reasons that necessitated such. Hydrogen (H 2) has been widely considered a clean fuel for the future, with the highest mass based energy density among known fuels. Bio-oil components are the most renewable energy carriers produced from bio-mass which have been selected for hydrogen production. Phenol and acetic acid are among the major liquid waste components of the bio oil. Catalytic steam reforming of these components in a fixed bed reactor provides a promising technique for hydrogen production from renewable sources. Due to the vital interaction that exists between catalyst and supports, Rh and Ni active metals and ZrO 2 , La 2 O 3 and CeO 2 supports were found to be appropriate catalysts with long-term stability for the hydrogen production via steam reforming of phenol and acetic acid. The process is advantageous due to its high hydrocarbon conversion and H 2 /CO 2 product ratio. The present work provides extensive information about the phenol and acetic acid steam reforming process for producing hydrogen as a renewal energy carrier.
Journal of Chemical Technology & Biotechnology, 2012
OVERVIEW: Efficient conversion of biomass to hydrogen is imperative in order to realize sustainable hydrogen production. Sorption enhanced steam reforming (SESR) is an emerging technology to produce high purity hydrogen directly from biomassderived oxygenates, by integrating steam reforming, water-gas shift and CO 2 separation in one-stage. Factors such as simplicity of the hydrogen production process, flexibility in feedstock, high hydrogen yield and low cost, make the SESR process attractive for biomass conversion to fuels. IMPACT: Recent work has demonstrated that SESR of biomass-derived oxygenates has greater potential than conventional steam reforming for hydrogen production. The flexibility of SESR processes resides in the diversity of feedstocks, which can be gases (e.g. biogas, syngas from biomass gasification), liquids (e.g. bioethanol, glycerol, sugars or liquid wastes from biomass processing) and solids (e.g. lignocellulosic biomass). SESR can be developed to realize a simple biomass conversion process but with high energy efficiency. APPLICATIONS: Hydrogen production by SESR of biomass-derived compounds can be integrated into existing oil refineries and bio-refineries for hydrotreating processing, making the production of gasoline and diesel greener. Moreover, hydrogen from SESR can be directly fed to fuel cells for power generation.
Energy, 2011
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 NieAl 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 H 2 /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.
Steam reforming of bio-oil: Effect of bio-oil composition and stability
2008
Hydrogen can be obtained from biomass pyrolysis liquids by catalytic steam reforming. Catalyst deactivation by coking and the formation of carbon deposits are the major known limitations although the specific causes are unidentified. It is proposed that these limitations could be reduced by selectively reforming specific fractions of the bio-oil. The hydrophobic fraction mainly composed of heavy oligomers can be