Cellulose Conversion for Bio-Ethanol

Softwood Saw Dust and DDGS Corn Fiber processing for BEI Dilute-Acid Cellulose Hydrolysis has been carried out with the BEI Refined Engineering Prototype Pilot Plant Processing System of the BEI CHP&RS.

The BEI-DACH-P&RS is comprised of two double-tube heat-exchanger plug-flow reactor (DT-HX-PFR) systems; which are as two-stages in series. It achieves substantially-higher than Known-Art performance; in the dilute-acid catalyzed hydrolysis conversion of Biomass Hemi- and Alpha-Cellulose (HC and AC) into highly-fermentable sugars. It there-in provides: (1) Lower cellulose hydrolyzate sugar decompositions; (2) reduced dilute-acid catalyzed cellulose hydrolysis reaction times, (3) increased reactor-processing capacities and (4) significant reductions; by re-use in sulfuric acid catalyst and hydrolysis process-heat; in the quantity requirements.

Unforeseen breakthroughs, from the Known-Art performances, are found in the US Patented and Canada Patented: "BEI-DACH-P&RS" which include the following: (1) Overall reductions in the dilute-acid catalyst requrements and costs to 66%, (2) overall reductions in the process heat requrement to 70% and (3) hydrolysis efficiency of the alpha-cellulose (AC) fraction to glucose of +10% to almost 80%. All-of-which are substantially above the performance in Known-Art for Two-Stage Dilute-Acid Ligno-Cellulose Hydrolysis Reaction Processes.

The BEI Cellulose Hydrolysis Process and Reactor System (BEI CHP&RS) has recently been developed by BEI chemical process engineering effort into "The BEI Refined Engineering Prototype" (REPT) system; which is located and operable at the BEI Pilot Plant Facility near Bozeman. Montana.  In 1991-93, under the first USDOE/C&RE/I&IP financial grant, BEI designed, assembled, checked out and limit-operated the BEI-CHP&RS REPT for the pilot plant process validation of the dilute-sulfuric acid hydrolysis of Pine Softwood waste feedstock into fermentable sugars.

For Pine Softwood (SW) cellulose hydrolysis, the reaction time for maximum sugar yields: (a) for SW-hemi-cellulose hydrolysis (HCH) hexoses and pentoses @ 140°C. w/ 1,75% dilute-acid was 7.7 minutes; which achieved an 0.80 fractional yield, and (b) for SW- alpha-cellulose hydrolysis (ACH) glucose @ 180°C. w/ 2.5% dilute-acid was 6.3 minutes; which achieved an 0.60 fractional yield; with single PFR pass; and an 0.65 with 50% recycle of unhydrolyzed AC for second PFR pass.   For information related to the BEI chemical process description report go to "Comparison of Cellulose Hydrolysis" linked (on contact BEI) page.

In 1998 BEI submitted a follow-up unsolicited proposal which was for the second part of the BEI-USDOE-C&RE-I&IP-ERIP Grant.  That Part 2 was for BEI to carry out, by use of the BEI-HP&RS REPT, the dilute-sulfuric-acid cellulose hydrolysis of DDGS Corn-Fiber, into fermentable sugars. During that Part 2 project. BEI requested and received Corn Fiber feedstock from several commercial corn starch to fuel ethanol production industry companies; which provided BEI adequate supplies of Distillers Dried Grains w/ Solubles (DDGS) from corn dry-milling FGE production, and Corn Gluten Feed (CGF) from corn wet-milling Fuel Ethanol production. The DDGS Corn-Fiber alpha-cellulose hydrolysate (ACH) maximum yield was found to be 65.4% to glucose @ 170°C. w/ 2.25pH and at 12.8 min reaction time. The Corn Fiber hemi-cellulose hydrolysate (HCH) maximum yield was found to be 57.0% to xylose @ 140°C. w/ 2.0 pH and at 18.3 min. reaction time.