108
A. R. Abouelela et al.
performance with recycled ionic liquid to quantify the recovery rate and its impact on
the cellulose-pulp composition and enzymatic digestibility. Recycling experiments
were conducted on M. giganteus using [N 0 2 2 2 ][HSO 4 ] at pretreatment conditions of
120 °C and 8 h. Over the course of four consecutive IL uses, the IL recovery achieved
was 98–99% [22]. These recoveries are much higher than the reported [C 2 C 1 im][Ace]
recovery (85–90%) [119, 120] and also higher than organic solvent recovery in the
organosolv process (96–98%) [67]. In addition, [N 0 2 2 2 ][HSO 4 ] recycling did not
have a negative effect on process performance. In fact, the glucose yields gradually
increased from 62 to 71% over three IL reuses, which was coupled with an increase of
the glucan recovery in the pulp. Both effects were attributed to the hypothesis that the
excess acid present in the first IL batch was consumed over the cycles causing more
glucan to be retained and higher glucose to be released in enzymatic hydrolysis. The
high IL recovery achieved in the ionoSolv process coupled with low IL cost shows
high promise to be able to compete with established pretreatment technologies.
5.6 Technology Validation in a Relevant Environment
(TRL 5-6)
A key step in the process development roadmap involves moving from the benchscale to a larger scale. The “larger scale” can be either a laboratory scale-up study,
where the process volume and equipment are scaled by several orders, or it can be
a pilot-scale demonstration. Usually, both are necessary before taking the process
to commercial operation. It is important at this stage for the process developers to
draw a conceptual engineering design to think about the process flow and choose
potential unit operations. This exercise coupled with the techno-economic evaluation
are powerful tools to identify key process and scale-up challenges that may not have
existed in a lab-scale environment.
5.6.1 Process Conceptual Design
Figure 5.7 shows a simplified process flow diagram of the ionoSolv process. The
unit operations discussed here might be changed and adapted to meet the specific
targets for a given project, such as cost cycle optimization, CAPEX minimization,
and the scale of the plant. The main sections in the process can be divided into feed
handling, pretreatment, lignin recovery, and IL regeneration. In feed handling, the
supplied biomass is stored and prepared where a chipper or a mill is used to reduce
the size of the biomass to facilitate pretreatment. In the pretreatment section, the
chipped biomass is brought into contact with a mixture of recycled ionic liquid and
water (typically 20% water content by weight) in a reactor and heated to temperatures
A. R. Abouelela et al.
performance with recycled ionic liquid to quantify the recovery rate and its impact on
the cellulose-pulp composition and enzymatic digestibility. Recycling experiments
were conducted on M. giganteus using [N 0 2 2 2 ][HSO 4 ] at pretreatment conditions of
120 °C and 8 h. Over the course of four consecutive IL uses, the IL recovery achieved
was 98–99% [22]. These recoveries are much higher than the reported [C 2 C 1 im][Ace]
recovery (85–90%) [119, 120] and also higher than organic solvent recovery in the
organosolv process (96–98%) [67]. In addition, [N 0 2 2 2 ][HSO 4 ] recycling did not
have a negative effect on process performance. In fact, the glucose yields gradually
increased from 62 to 71% over three IL reuses, which was coupled with an increase of
the glucan recovery in the pulp. Both effects were attributed to the hypothesis that the
excess acid present in the first IL batch was consumed over the cycles causing more
glucan to be retained and higher glucose to be released in enzymatic hydrolysis. The
high IL recovery achieved in the ionoSolv process coupled with low IL cost shows
high promise to be able to compete with established pretreatment technologies.
5.6 Technology Validation in a Relevant Environment
(TRL 5-6)
A key step in the process development roadmap involves moving from the benchscale to a larger scale. The “larger scale” can be either a laboratory scale-up study,
where the process volume and equipment are scaled by several orders, or it can be
a pilot-scale demonstration. Usually, both are necessary before taking the process
to commercial operation. It is important at this stage for the process developers to
draw a conceptual engineering design to think about the process flow and choose
potential unit operations. This exercise coupled with the techno-economic evaluation
are powerful tools to identify key process and scale-up challenges that may not have
existed in a lab-scale environment.
5.6.1 Process Conceptual Design
Figure 5.7 shows a simplified process flow diagram of the ionoSolv process. The
unit operations discussed here might be changed and adapted to meet the specific
targets for a given project, such as cost cycle optimization, CAPEX minimization,
and the scale of the plant. The main sections in the process can be divided into feed
handling, pretreatment, lignin recovery, and IL regeneration. In feed handling, the
supplied biomass is stored and prepared where a chipper or a mill is used to reduce
the size of the biomass to facilitate pretreatment. In the pretreatment section, the
chipped biomass is brought into contact with a mixture of recycled ionic liquid and
water (typically 20% water content by weight) in a reactor and heated to temperatures