5 Commercial Aspects of Biomass Deconstruction with Ionic Liquids
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process, it was shown that the M. giganteus pretreatment can be conducted with 10–
40 wt% IL concentration [87], which gives larger flexibility to use a less intensive
washing procedure. The lab-scale protocol of the ionoSolv process was optimized
using ethanol as a washing solvent to give clean NMR spectra and to make sure that
enzymatic saccharification is not inhibited by residual IL. Indeed, the practice is not
representative of an industrial-scale process. Instead, a two-step washing procedure
is suggested in the conceptual design of the process. The cellulose-rich pulp will
be washed with a split stream of the lean hot recycled IL to remove the residual IL
coating the pulp surface followed by a water wash to ensure efficient pulp washing
and cleaning from inhibitory compounds. Washing with the lean hot IL stream will
add three main benefits compared to a direct water wash configuration: (1) it will
minimize IL losses as the residual IL will loop back to process, (2) it will minimize
sending residual IL to the wastewater unit, and (3) it will potentially promote further
lignin extraction from the pulp.
5.6.4 Materials of Construction
Protecting the production plant’s integrity is a top priority of any industrial process as
it directly impacts the safety and reliability of the operation. Selecting the appropriate
materials of construction is, therefore, a key step in the process of scaling-up a
technology. The selection process depends on several factors, mainly: (1) corrosion
or degradation resistance of the material against processing fluids, (2) cost of the
material selected and its contribution to the total capital cost, and (3) expected life
of operation and type of process (i.e., continuous vs. batch) [43]. Metals and their
alloys have been the most dominant construction materials in the industry. Over the
decades, academic research and industrial experience have established an in-depth
understanding of corrosion behavior and the mechanism and methods of protection
of metals in conventional corrosive environments, such as saline water and acidic
solutions. On the other hand, research on understanding the corrosion behavior of
metals in ILs is scarce with existing studies focusing mainly on fluorine-containing
ILs or functionalized ILs [128, 136–138]. However, the study of several classes of ILs
as corrosion inhibitors has shown promising corrosion inhibition effects [139–141].
Uerdingen et al. conducted one of the first studies to investigate the corrosion
behavior of common construction metals using several ILs [142]. The study highlighted how the chemical structure of the IL cation and the nature of the anion have
a significant impact on the IL corrosive behavior.
In a pilot or industrial-scale operation of an IL-based pretreatment process, the
pretreatment reactor’s material compatibility with the hot ionic liquid needs to be
known in advance. Corrosion rate is expressed in millimetres of metal lost per year
(mm/y) and is used to indicate the corrosion severity during operation. It is a common
industrial practice to use the corrosion rate value estimated in lab-scale or pilotscale studies of an average cost material to permit some thickness allowance in the
design specifications. As a general guideline in corrosion handbooks, corrosion rates
113
process, it was shown that the M. giganteus pretreatment can be conducted with 10–
40 wt% IL concentration [87], which gives larger flexibility to use a less intensive
washing procedure. The lab-scale protocol of the ionoSolv process was optimized
using ethanol as a washing solvent to give clean NMR spectra and to make sure that
enzymatic saccharification is not inhibited by residual IL. Indeed, the practice is not
representative of an industrial-scale process. Instead, a two-step washing procedure
is suggested in the conceptual design of the process. The cellulose-rich pulp will
be washed with a split stream of the lean hot recycled IL to remove the residual IL
coating the pulp surface followed by a water wash to ensure efficient pulp washing
and cleaning from inhibitory compounds. Washing with the lean hot IL stream will
add three main benefits compared to a direct water wash configuration: (1) it will
minimize IL losses as the residual IL will loop back to process, (2) it will minimize
sending residual IL to the wastewater unit, and (3) it will potentially promote further
lignin extraction from the pulp.
5.6.4 Materials of Construction
Protecting the production plant’s integrity is a top priority of any industrial process as
it directly impacts the safety and reliability of the operation. Selecting the appropriate
materials of construction is, therefore, a key step in the process of scaling-up a
technology. The selection process depends on several factors, mainly: (1) corrosion
or degradation resistance of the material against processing fluids, (2) cost of the
material selected and its contribution to the total capital cost, and (3) expected life
of operation and type of process (i.e., continuous vs. batch) [43]. Metals and their
alloys have been the most dominant construction materials in the industry. Over the
decades, academic research and industrial experience have established an in-depth
understanding of corrosion behavior and the mechanism and methods of protection
of metals in conventional corrosive environments, such as saline water and acidic
solutions. On the other hand, research on understanding the corrosion behavior of
metals in ILs is scarce with existing studies focusing mainly on fluorine-containing
ILs or functionalized ILs [128, 136–138]. However, the study of several classes of ILs
as corrosion inhibitors has shown promising corrosion inhibition effects [139–141].
Uerdingen et al. conducted one of the first studies to investigate the corrosion
behavior of common construction metals using several ILs [142]. The study highlighted how the chemical structure of the IL cation and the nature of the anion have
a significant impact on the IL corrosive behavior.
In a pilot or industrial-scale operation of an IL-based pretreatment process, the
pretreatment reactor’s material compatibility with the hot ionic liquid needs to be
known in advance. Corrosion rate is expressed in millimetres of metal lost per year
(mm/y) and is used to indicate the corrosion severity during operation. It is a common
industrial practice to use the corrosion rate value estimated in lab-scale or pilotscale studies of an average cost material to permit some thickness allowance in the
design specifications. As a general guideline in corrosion handbooks, corrosion rates