Biomedical Engineering Reference
In-Depth Information
4.5
Selectively Structural Fractionation
4.5.1
Development History of Selectively Structural
Fractionation
4.5.1.1
Functionally Whole Conversion
There is a long history of biomass utilization by human beings. Papermaking
and charcoal manufacturing techniques in ancient Egypt are successful examples
of biomass utilization. But, after the discovery of oil and coal, the development
of new energy and a chemical industry based on them greatly facilitated the
development of civilization and made biomass utilization slowly fade. The first
global oil crisis in 1973 made the study of biomass regain attention. At first,
research of biomass mainly focused on the use of biomass to obtain energy heat,
electricity, or fuels such as ethanol and now focus on developing various conversion
technologies.
China is a large agricultural country with a long history of recycling straw-
based biomass resources, including compost, returning it to the field, forage, fuel,
and so on. However, because of the limitations of the times and technology,
conversion of biomass has some problems, such as the low-level utilization and
low utilization efficiency. With the development of technology, biomass conversion
technologies continue to improve, and its conversion rate also gradually increases.
In the twentieth century, with the development of technology and the aggravation
of the energy crisis, the research of biomass utilization rapidly developed; biomass
gasification and biomass liquefaction have achieved certain results.
The direct combustion, gasification, pyrolysis, liquefaction, and other biomass
utilization technologies focus on the overall function conversion of biomass feed-
stock, but biomass is a structurally complex, functional supramolecular structure;
using overall function conversion to achieve the primary refining of biomass
feedstock, it is impossible to achieve the maximum value of the biomass materials.
4.5.1.2
Fully Functional Conversion
The complex composition of biomass determines that the biomass feedstock is a
functional macromolecule body, and the different components are able to generate
different functional products. Thus, in addition to the direct combustion and other
fully functional conversions, based on the three main components of cellulose,
hemicellulose, and lignin utilization, a series of studies has been carried out and
has made some progress.
The paper industry mainly uses the cellulose component; therefore, it needs
to adopt various means to remove the hemicellulose and lignin. Thus, the other
