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Tucker, Melvin

Publications and source records attributed to Tucker, Melvin.

15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Effect of Feedstock Variability, Feedstock Blends, and Pretreatment Conditions on Sugar Yield and Production Costs

Mass production of sustainable biofuels replacing fossil fuels will significantly reduce global greenhouse gas emissions. However, biomass feedstock variability, availability, and affordability pose significant risks for the sustainable production of biofuels in biorefinery plants. To derisk the sustainable production of biofuels, this work investigates the sugar yields and production costs of four different feedstocks as well as their blends, using different pretreatment methods: deacetylation and dilute acid pretreatment (DDA) and deacetylation and mechanical refining pretreatment (DMR). We found that not only feedstock species variability, but also feedstock harvesting techniques have large impacts on both sugar yields and production costs. Single-pass harvested corn stover (SPCS) showed higher sugar yields and lower production costs than multipass harvested corn stover, followed by sorghum and switchgrass. The highest glucose yields of 91% and 95.3%, which corresponds to the lowest sugar production costs of $0.2286/lb. and $0.2490/lb., were observed for SPCS using DDA and DMR, respectively. The difference in sugar yields and production costs due to feedstock variability can be largely mitigated by increasing deacetylation severity, especially in DMR. Higher deacetylation severity resulted in decreased sugar production costs in the case of DMR in contrast to increased costs in the case of DDA. Blending switchgrass and sorghum into corn stover, which can significantly increase the feedstock availability and sustainability, resulted in sugar yields and production costs of roughly the weighted average of those derived from constituent individual feedstocks, respectively. Thus, blending feedstocks of different biomass species is a potential successful strategy for sustainable production of biofuels to replace fossil-derived fuels.

09 BIOMASS FUELS↗
DOE OSTI2019

Recycling of Dilute Deacetylation Black Liquor to Enable Efficient Recovery and Reuse of Spent Chemicals and Biomass Pretreatment Waste

Previous publications showed deacetylation/dilute alkaline pretreatment followed by mechanical refining (DMR) is an effective process for overcoming biomass recalcitrance. To successfully commercialize alkaline-based pretreatments, we pioneered a new process modification and strategy to recycle and reuse the weak black liquor (WBL) to reduce water, chemical, and energy usage while increasing the solids, sodium, acetate, sugars, and lignin contents in the weak black liquor. Our results suggest that the accumulation of both chemicals and organic matter did not reduce acetyl and lignin removal in alkaline pretreatment, resulting in comparable sugar yields in enzymatic hydrolysis. Sodium and potassium were found to be the two most important inorganic substances in the recycled weak black liquor. Moreover, the accumulated sodium and phenolic compounds did not inhibit the downstream fermentation and ethanol fermentation processes. Finally, techno-economic analysis (TEA) showed the recycling of weak black liquor could decrease the minimum ethanol selling price (MESP) by approximately 5 to 15 cents per gallon of ethanol when compared to a conventional non-recycling process. solids, sodium, acetate, sugars, and lignin contents in the weak black liquor. Our results suggest that the accumulation of both chemicals and organic matter did not reduce acetyl and lignin removal in alkaline pretreatment, resulting in comparable sugar yields in enzymatic hydrolysis. Sodium and potassium were found to be the two most important inorganic substances in the recycled weak black liquor. Moreover, the accumulated sodium and phenolic compounds did not inhibit the downstream fermentation and ethanol fermentation processes. Finally, techno-economic analysis (TEA) showed the recycling of weak black liquor could decrease the minimum ethanol selling price (MESP) by approximately 5 to 15 cents per gallon of ethanol when compared to a conventional non-recycling process.

09 BIOMASS FUELS↗
DOE OSTI2018

Kinetics and Rheological Behavior of Higher Solid (Solids >20%) Enzymatic Hydrolysis Reactions Using Dilute Acid Pretreated, Deacetylation and Disk Refined, and Deacetylation and Mechanical Refined (DMR) Corn Stover Slurries

Many potential biochemical pathways producing advanced hydrocarbon fuels from renewable lignocellulosic biomass require hydrolysates with high sugar concentrations and low toxicity, enabling flexible fermentation strategies, such as fed-batch fermentations capable of producing high product titers and production rates during fermentation. High sugar concentrations also increase the osmotic pressure in the hydrolysates, thus helping to decrease contamination issues. We have shown the production of high sugar concentrations directly from biomass without the need for energy/capital intensive concentration, conditioning, and/or purification steps. In our previous work, we successfully demonstrated high biomass-derived sugar concentrations (over 230 g/L fermentable sugars) in enzymatic hydrolysis from high solid (>20 wt % insoluble solids) digestions of dilute alkali deacetylated and mechanically refined (DMR) corn stover slurries. The goal of this work was to understand the effects of initial solid loadings on differently pretreated corn stover substrates on the rheological property changes of enzymatic-hydrolyzed slurries as well as the rates and yields of the enzymatic hydrolysis reactions. We performed high-solid enzymatic hydrolysis using deacetylated and disk refined (DDR), DMR, and dilute acid pretreated (DAP) corn stover substrates at four different initial total solid loadings, 17, 22, 27, and 32%. Slurry samples were collected at regular intervals for measurements of monomeric and oligomeric sugar concentrations (glucose and xylose), particle size distributions, viscosities, and yield stresses. We produced over 270 g/L of fermentable, monomeric sugars (157 g/L of glucose and 114 g/L of xylose) at 32 wt % total insoluble solid during enzymatic hydrolysis of the DMR substrates. The pumpabilities of the digested, high-solid enzymatic hydrolysates were shown to be comparable to other commercially relevant slurry streams, such as honey, peanut butter, and ketchup from the food industry. The conversion and rheological results indicate that high-solid enzymatic hydrolysis (~33 wt %) of DMR substrates is a promising and scalable technology for producing high sugar concentration slurries from lignocellulosic biomass.

09 BIOMASS FUELS↗
DOE OSTI2016

Sweet sorghum bagasse and corn stover serving as substrates for producing sophorolipids

To make the process of producing sophorolipids by Candida bombicola truly sustainable, we investigated production of these biosurfactants on biomass hydrolysates. This study revealed: (1) yield of sophorolipds on bagasse hydrolysate decreased from 0.56 to 0.54 and to 0.37 g/g carbon source when yellow grease was dosed at 10, 40 and 60 g/L, respectively. In the same order, concentration of sophorolipids was 35.9, 41.9, and 39.3 g/L; (2) under similar conditions, sophorolipid yield was 0.12, 0.05 and 0.04 g/g carbon source when corn stover hydrolysate was mixed with soybean oil at 10, 20 and 40 g/L. Sophorolipid concentration was 11.6, 4.9, and 3.9 g/L for the three oil doses from low to high; and (3) when corn stover hydrolysate and yellow grease served as the substrates for cultivating the yeast in a fermentor, sophorolipid concentration reached 52.1 g/L. Upon further optimization, sophorolipids production from ligocellulose will be indeed sustainable.

09 BIOMASS FUELS↗
DOE OSTI2014

Kinetic features of xylan de-polymerization in production of xylose monomer and furfural during acid pretreatment for kenaf, forage sorghums and sunn hemp feedstocks

A kinetic study of acid pretreatment was conducted for sorghum non-brown mid rib (SNBMR) ( Sorghum bicolor L Moench ), sorghum-brown mid rib (SBMR), sunn hemp ( Crotalaria juncea L ) and kenaf ( Gossypiumhirsutum L ), focusing on rates of xylose monomer and furfural formation. The kinetics was investigated using two independent variables, reaction temperature (150 and 160°C) and acid concentration (1 and 2 wt%), with a constant dry biomass loading of 10 wt% and a treatment time up to 20 min while sampling the mixture every 2 min. The experimental data were fitted using a two-step kinetic model based on irreversible pseudo first order kinetics at each step. Varied kinetic orders on the acid concentration, ranging from 0.2 to >3, were observed for both xylose and furfural formation, the values depending on the feedstock. The crystallinity index of raw biomass was shown to be a major factor influencing the rate of both xylose and furfural formation. As a result, a positive correlation was observed between the activation energy and biomass crystallinity index for xylose formation.

09 BIOMASS FUELS↗
DOE OSTI2013

Recent Development in Chemical Depolymerization of Lignin: A Review

This article reviewed recent development of chemical depolymerization of lignins. There were five types of treatment discussed, including base-catalyzed, acid-catalyzed, metallic catalyzed, ionic liquids-assisted, and supercritical fluids-assisted lignin depolymerizations. The methods employed in this research were described, and the important results were marked. Generally, base-catalyzed and acid-catalyzed methods were straightforward, but the selectivity was low. The severe reaction conditions (high pressure, high temperature, and extreme pH) resulted in requirement of specially designed reactors, which led to high costs of facility and handling. Ionic liquids, and supercritical fluids-assisted lignin depolymerizations had high selectivity, but the high costs of ionic liquids recycling and supercritical fluid facility limited their applications on commercial scale biomass treatment. Metallic catalyzed depolymerization had great advantages because of its high selectivity to certain monomeric compounds and much milder reaction condition than base-catalyzed or acid-catalyzed depolymerizations. It would be a great contribution to lignin conversion if appropriate catalysts were synthesized.

Wang, Hai↗
DOE OSTI2012

Effects of Dilute Acid Pretreatment on Cellulose DP and the Relationship Between DP Reduction and Cellulose Digestibility

The degree of polymerization(DP) of cellulose is considered to be one of the most important properties affecting the enzymatic hydrolysis of cellulose. Various pure cellulosic and biomass materials have been used in a study of the effect of dilute acid treatment on cellulose DP. A substantial reduction in DP was found for all pure cellulosic materials studied even at conditions that would be considered relatively mild for pretreatment. The effect of dilute acid pretreatment on cellulose DP in biomass samples was also investigated. Corn stover pretreated with dilute acid under the most optimal conditions contained cellulose with a DPw in the range of 1600{approx}3500, which is much higher than the level-off DP(DPw 150{approx}300) obtained with pure celluloses. The effect of DP reduction on the saccharification of celluloses was also studied. From this study it does not appear that cellulose DP is a main factor affecting cellulose saccharification.

09 BIOMASS FUELS↗
DOE OSTI2011

Treatment of biomass to obtain fermentable sugars

Biomass is pretreated using a low concentration of aqueous ammonia at high biomass concentration. Pretreated biomass is further hydrolyzed with a saccharification enzyme consortium. Fermentable sugars released by saccharification may be utilized for the production of target chemicals by fermentation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Speaker Abstracts

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09 BIOMASS FUELS↗