https://cmapspublic3.ihmc.us/rid=1N3976C22-12M3P49-9V/Holladay%20et%20al.%20-%202009%20-%20An%20overview%20of%20hydrogen%20production%20technologies.pdf

An overview of hydrogen production technologies

Hydrothermal technologies are broadly defined as chemical and physical transformations in high-temperature (200–600 °C), high-pressure (5–40 MPa) liquid or supercritical water. This thermochemical means of reforming biomass may have energetic advantages, since, when water is heated at high pressures a phase change to steam is avoided which avoids large enthalpic energy penalties. Biological chemicals undergo a range of reactions, including dehydration and decarboxylation reactions, which are influenced by the temperature, pressure, concentration, and presence of homogeneous or heterogeneous catalysts. Several biomass hydrothermal conversion processes are in development or demonstration. Liquefaction processes are generally lower temperature (200–400 °C) reactions which produce liquid products, often called “bio-oil” or “bio-crude”. Gasification processes generally take place at higher temperatures (400–700 °C) and can produce methane or hydrogen gases in high yields.

/pdf/thermochemical-biofuel-production-in-hydrothermal-media-a-57itjyvhnt.pdf

Thermochemical biofuel production in hydrothermal media: A review of sub- and supercritical water technologies

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

As the oil reserves are depleting the need of an alternative fuel source is becoming increasingly apparent. One prospective method for producing fuels in the future is conversion of biomass into bio-oil and then upgrading the bio-oil over a catalyst, this method is the focus of this review article. Bio-oil production can be facilitated through flash pyrolysis, which has been identified as one of the most feasible routes. The bio-oil has a high oxygen content and therefore low stability over time and a low heating value. Upgrading is desirable to remove the oxygen and in this way make it resemble crude oil. Two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking. HDO is a high pressure operation where hydrogen is used to exclude oxygen from the bio-oil, giving a high grade oil product equivalent to crude oil. Catalysts for the reaction are traditional hydrodesulphurization (HDS) catalysts, such as Co–MoS2/Al2O3, or metal catalysts, as for example Pd/C. However, catalyst lifetimes of much more than 200 h have not been achieved with any current catalyst due to carbon deposition. Zeolite cracking is an alternative path, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenation reaction. In these systems hydrogen is not a requirement, so operation is performed at atmospheric pressure. However, extensive carbon deposition results in very short catalyst lifetimes. Furthermore a general restriction in the hydrogen content of the bio-oil results in a low H/C ratio of the oil product as no additional hydrogen is supplied. Overall, oil from zeolite cracking is of a low grade, with heating values approximately 25% lower than that of crude oil. Of the two mentioned routes, HDO appears to have the best potential, as zeolite cracking cannot produce fuels of acceptable grade for the current infrastructure. HDO is evaluated as being a path to fuels in a grade and at a price equivalent to present fossil fuels, but several tasks still have to be addressed within this process. Catalyst development, understanding of the carbon forming mechanisms, understanding of the kinetics, elucidation of sulphur as a source of deactivation, evaluation of the requirement for high pressure, and sustainable sources for hydrogen are all areas which have to be elucidated before commercialisation of the process.

A review of catalytic upgrading of bio-oil to engine fuels

Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine-tuning of multiple "upstream" (i.e., lignin bioengineering, lignin isolation and "early-stage catalytic conversion of lignin") and "downstream" (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a "beginning-to-end" analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis.

https://tpbin.com/Uploads/Subjects/c40ab809-7c5f-469c-b983-d02e51b67a81.pdf

A review of catalytic hydrodeoxygenation of lignin-derived phenols from biomass pyrolysis.

A review and perspective of recent bio-oil hydrotreating research

Wet algae slurries can be converted into an upgradeable biocrude by hydrothermal liquefaction (HTL). High levels of carbon conversion to gravity separable biocrude product were accomplished at relatively low temperature (350 °C) in a continuous-flow, pressurized (sub-critical liquid water) environment (20 MPa). As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent and biomass trace components were removed by processing steps so that they did not cause process difficulties. High conversions were obtained even with high slurry concentrations of up to 35 wt.% of dry solids. Catalytic hydrotreating was effectively applied for hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization of the biocrude to form liquid hydrocarbon fuel. Catalytic hydrothermal gasification was effectively applied for HTL byproduct water cleanup and fuel gas production from water soluble organics, allowing the water to be considered for recycle of nutrients to the algae growth ponds. As a result, high conversion of algae to liquid hydrocarbon and gas products was found with low levels of organic contamination in the byproduct water. All three process steps were accomplished in bench-scale, continuous-flow reactor systems such that design data for process scale-up was generated.

/pdf/process-development-for-hydrothermal-liquefaction-of-algae-3q34anbmn8.pdf

Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor

Catalytic hydroprocessing has been applied to biomass fast pyrolysis liquid product (bio-oil) in a bench-scale continuous-flow fixed-bed reactor system The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock The project was a cooperative research and development agreement among UOP LLC, the National Renewable Energy Laboratory and the Pacific Northwest National Laboratory (PNNL) This article is focused on the process experimentation and product analysis undertaken at PNNL

This article describes the experimental methods used and relates the results of the product analyses A range of catalyst formulations were tested over a range of operating parameters including temperature, pressure, and flow rate with bio-oil derived from several different biomass feedstocks Effects of liquid hourly space velocity and catalyst bed temperature were assessed Details of the process results were presented included product yields and hydrogen consumption Detailed analysis of the products were provided including elemental composition, chemical functional type determined by mass spectrometry, and product descriptors such as density, viscosity, and total acid number In conclusion, this article provides an understanding of the efficacy of hydroprocessing as applied to bio-oil © 2009 American Institute of Chemical Engineers Environ Prog, 2009

Catalytic Hydroprocessing of Biomass Fast Pyrolysis Bio-oil to Produce Hydrocarbon Products

Catalytic hydroprocessing has been applied to the fast pyrolysis liquid product (bio-oil) from softwood biomass in a bench-scale continuous-flow fixed-bed reactor system. The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock. This paper is focused on the process experimentation and product analysis. A range of operating parameters, including temperature from 170 or 250 to 400 °C in the two-stage reactor and flow rate of 0.19 liquid hourly space velocity, was tested with bio-oil derived from pine wood. Times on stream of up to 90 h were evaluated, and losses of catalyst activity were assessed. Product yields of 0.35–0.45 g of oil product/g of dry bio-oil feed with hydrogen consumptions from 342 to 669 L/L of bio-oil feed were measured. Analyses determined that product oils with densities of 0.82–0.92 g/mL had oxygen contents of 0.2–2.7 wt % and total acid number (TAN) o...

Alan H. Zacher

Papers

A review of catalytic hydrodeoxygenation of lignin-derived phenols from biomass pyrolysis.

A review and perspective of recent bio-oil hydrotreating research

Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor

Catalytic Hydroprocessing of Biomass Fast Pyrolysis Bio-oil to Produce Hydrocarbon Products

Catalytic Hydroprocessing of Fast Pyrolysis Bio-oil from Pine Sawdust