This paper provides an updated review on fast pyrolysis of biomass for production of a liquid usually referred to as bio-oil. The technology of fast pyrolysis is described including the major reaction systems. The primary liquid product is characterised by reference to the many properties that impact on its use. These properties have caused increasingly extensive research to be undertaken to address properties that need modification and this area is reviewed in terms of physical, catalytic and chemical upgrading. Of particular note is the increasing diversity of methods and catalysts and particularly the complexity and sophistication of multi-functional catalyst systems. It is also important to see more companies involved in this technology area and increased take-up of evolving upgrading processes. © 2011 Elsevier Ltd.

Review of fast pyrolysis of biomass and product upgrading

Green roof performance towards management of runoff water quantity and quality: A review

Biomass can be utilized to produce bio-oil, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion of biomass to bio-oil: flash pyrolysis and hydrothermal liquefaction. The cost of bio-oil production from biomass is relatively high based on current technologies, and the main challenges are the low yield and poor bio-oil quality. Considerable research efforts have been made to improve the bio-oil production from biomass. Scientific and technical developments towards improving bio-oil yield and quality to date are reviewed, with an emphasis on bio-oil upgrading research. Furthermore, the article covers some major issues that associated with bio-oil from biomass, which includes bio-oil basics (e.g., characteristics, chemistry), application, environmental and economic assessment. It also points out barriers to achieving improvements in the future.

Bio-oil production and upgrading research: A review

The rapid depletion of conventional fossil fuels and day-by-day growth of environmental pollution due to use of extensive use of fossil fuels have raised concerns over the use of the fossil fuels; and thus search for alternate renewable and sustainable sources for fuels has started in the last few decades. In this context biomass derived fuels seems to be the promising path; and various routes are available for the biomass processing such as pyrolysis, transesterification, hydrothermal liquefaction, steam reforming, etc.; and the hydrothermal liquefaction (HTL) of wet biomass seems to be the promising route. Therefore, this article briefly enlightened a few concepts of HTL such as the elemental composition of bio-crude obtained by HTL, different types of feedstock adopted for HTL, mechanism of HTL processes, possible process flow diagrams for HTL of both wet and dry biomass and energy efficiency of the process. In addition, this article also enlisted possible future research scope for concerned researchers and a few of them are setting up HTL plant suitable for both wet and dry biomass feedstock; analysing influence of parameters such as temperature, pressure, residence time, catalytic effects, etc.; deriving optimized pathways for better conversion; and development of theoretical models representing the process to the best possible accuracy depending on nature of feedstock.

A review on hydrothermal liquefaction of biomass

The HYDRUS-1D and HYDRUS (2D/3D) computer software packages are widely used finite-element models for simulating the one- and two- or three-dimensional movement of water, heat, and multiple solutes in variably saturated media, respectively. In 2008, Simůnek et al. (2008b) described the entire history of the development of the various HYDRUS programs and related models and tools such as STANMOD, RETC, ROSETTA, UNSODA, UNSATCHEM, HP1, and others. The objective of this manuscript is to review selected capabilities of HYDRUS that have been implemented since 2008. Our review is not limited to listing additional processes that were implemented in the standard computational modules, but also describes many new standard and nonstandard specialized add-on modules that significantly expanded the capabilities of the two software packages. We also review additional capabilities that have been incorporated into the graphical user interface (GUI) that supports the use of HYDRUS (2D/3D). Another objective of this manuscript is to review selected applications of the HYDRUS models such as evaluation of various irrigation schemes, evaluation of the effects of plant water uptake on groundwater recharge, assessing the transport of particle-like substances in the subsurface, and using the models in conjunction with various geophysical methods.

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Recent Developments and Applications of the HYDRUS Computer Software Packages

Modeling stormwater runoff from green roofs with HYDRUS-1D

Comparison of three accelerated aging procedures to assess bio-oil stability

Pyrolysis of solid biomass, in this case pine pellets and peanut hulls, generates a hydrocarbon-rich liquid product (bio-oil) consisting of oily and aqueous phases. Here, each phase is characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to yield unique elemental compositions for thousands of compounds. Bio-oils are dominated by Ox species: few oxygens per molecule for the oily phase and many more oxygens per molecules for the aqueous phase. Thus, the increased oxygen content per molecule accounts for its water solubility. Peanut hull bio-oil is much more compositionally complex and contains more nitrogen-containing compounds than pine pellet bio-oil. Bulk C, H, N, O, and S measurements confirm the increased levels of nitrogen-containing species identified in the peanut hull pyrolysis oil by FT-ICR MS. The ability of FT-ICR MS to identify and assign unique elemental compositions to compositionally complex bio-oils based on ultrah...

Characterization of Pine Pellet and Peanut Hull Pyrolysis Bio-oils by Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

A simple reactive condensation technique was developed to decrease the concentration of reactive species in the oily phase of two-phase pyrolysis oil as a means to increase the storage stability, heating value, and overall quality of the oil. Bio-oil vapor was esterified from the reaction of in situ organic acids with ethanol during condensation resulting in the production of water and esters. The research compared the quality of slow pyrolysis-produced bio-oils collected by condensing pyrolysis vapor using atomized ethanol (EtOH) at various weight hourly space velocity (WHSV). The resultant bio-oil exhibited two phases at room temperature, which were separated to obtain an oily and an aqueous phase. WHSV was varied from 8.3 to 33 (kg h−1 biomass per kg h−1 ethanol), which produced bio-oils with ethanol content ranging from 7.3 to 23.2 wt % of total oil. Increasing EtOH from 0 to 23% (w/w) decreased water content and viscosity in the oily phase by 16% and 56%, respectively, while also increasing pH from 2...

In-Line Esterification of Pyrolysis Vapor with Ethanol Improves Bio-oil Quality

Staged, low and high-temperature subcritical liquefaction were used to pretreat algae and generate a biocrude primarily characterized by free fatty acids and unsaturated hydrocarbons with reduced nitrogen heteroatom levels. Subsequently, catalytic hydrodenitrogenation and deoxygenation (HDN/HDO) was conducted using ruthenium (5% Ru/carbon) and cobalt molybdenum catalysts. Ru on carbon was the most effective HDO catalyst and generated the lowest level of nitrogen and heteroatoms in the resulting oil. A CoMo-S catalyst generated higher nitrogen and heteroatom levels, and resulted in a higher TAN value and lower heating value, probably due to the low sulfur levels in the biocrude. The highest quality oil was generated from a raceway strain using Ru/C and HTL pretreatment (225 °C, 15 min) with a repeated batch HDN/HDO step (3.24% N, 8.2% O, TAN of 12, 1.25% water, HHV 40 MJ/kg) and had a boiling point range of ~ 20% kerosene, ~ 30% distillate fuel oil, and ~ 50% gas oil. A 57% reduction in nitrogen content of the oil was realized when repeated HDN/HDO was coupled with HTL pretreatment using Ru/C (4.3 wt.%N), relative to 7.5%N for single stage HTL/HDO. Final yields for the highest quality oil generated via the coupled HTL/HDO process ranged from 15 to 22%. Recovery and reuse of the catalyst (Ru/C) resulted in a significant decline in activity potentially caused by coking and metals deposition.

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Roger N. Hilten

Papers

Modeling stormwater runoff from green roofs with HYDRUS-1D

Comparison of three accelerated aging procedures to assess bio-oil stability

Characterization of Pine Pellet and Peanut Hull Pyrolysis Bio-oils by Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

In-Line Esterification of Pyrolysis Vapor with Ethanol Improves Bio-oil Quality

Effect of low temperature hydrothermal liquefaction on catalytic hydrodenitrogenation of algae biocrude and model macromolecules