Hydrothermal refining of biomass - an overview and future perspectives

Abstract

Biomass is a promising alternative for the production of energy, novel materials, chemicals, and other valuable products. A certain degree of processing is required to achieve those results. Hydrothermal processes offer a unique way to obtain a wide range of biorefinery products. They can be considered as environmentally friendly processes, using solely water at different temperatures as a process medium to convert abundant and inexpensive biomass into products. We provide a short overview on hydrothermal processes that use water in its liquid state, including hot water extraction, pressurized hot water extraction, liquid hot water pretreatment, hydrothermal carbonization, and hydrothermal liquefaction. We also provide examples of current research and realworld findings. We then present a novel hydrothermal biorefinery concept for sequencing these single processes, giving concrete examples of possible raw materials and products. Sequencing gives new possibilities for biorefineries to exploit all the biomass components as valuable products with zero losses. The added value comes from the increased efficiency of the bio-based products’ value chain, by reducing losses and generating higher-value products and services.

Pressurized hot water extraction of Scots pine sapwood: effect of wood size on obtained treatment products

“…Pressurized hot water extraction (HWE) is based on treating wood in water that is heated to temperatures between 100 and 240°C and kept in liquid phase with sufficiently high pressure [1,2]. Studies on HWE are typically applied to wood sawdust, particles, or chips [1] to obtain hemicelluloses that can be utilized as feedstock for biofuel production [2,3] or for the conversion into high-value-added products [2,4,5].…”

Hydrogen production via aqueous-phase reforming of methanol over nickel modified Ce, Zr and La oxide supports

“…The highest activity and hydrogen selectivity in reforming reactions have typically been achieved over Pt-based catalysts, especially Pt supported on γ-Al2O3 [2][3][4]. However, comparable activities were achieved over cheaper nickel catalysts [5]. Nickel supported catalysts have generally shown high conversion and high hydrogen selectivity [5].…”

“…However, comparable activities were achieved over cheaper nickel catalysts [5]. Nickel supported catalysts have generally shown high conversion and high hydrogen selectivity [5]. However, the most tested nickel-based catalysts deactivated rapidly, due to the changing of the oxidation state of Ni, sintering or structural changes of the support [6].…”

Poultry By-products as a Potential Source of Nutrients

“…In hydrothermal processing raw material is heated at elevated temperature and pressure using water as a reaction medium to produce a range of valuable products [7][8][9]. Processing between 100 and 180°C is usually referred as hot water extraction and it results in the extraction of inorganics and hydrolysis of carbohydrates [10].…”

“…When the temperature is increased to the range of 180-250°C, the organic raw material starts to carbonize and the process is called hydrothermal carbonization (HTC) [8]. In hydrothermal liquefaction (HTL) at 280-370°C biocrude oil-like component is produced with increasing amount of gas [9]. Benefits of using hydrothermal processing for animal wastes are the destruction of pathogens typically present in such raw materials [10] and the fact that wet raw materials can be used without energy intense drying step.…”