Alcohols as H-donor media in coal conversion. 2. Base-promoted H-donation to coal by methyl alcohol

Ross, David S.; Blessing, James E.

doi:10.1016/0016-2361(79)90085-1

Cited by 76 publications

(16 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[50][51][52][53][54][55][56][57] It has also been shown potassium isopropoxide aids in transfer hydrogenation from iso-propanol to coal in the formation of acetone and the equivalent of H2 transfer to substrate. 58 In our work, the observation of acetone in the liquid phase after reaction with OPL (Figure S3) clearly indicates that i-PrOH is the major source of hydrogen reducing equivalents needed for HTH of OPL. Hydrogen donor solvents such as i-PrOH have also been used to suppress reactions of radical intermediates produced in the high temperature pyrolysis of lignins.…”

Section: Discussionsupporting

confidence: 55%

Hydrogenolysis of Organosolv Lignin in Ethanol/Isopropanol Media without Added Transition-Metal Catalyst

Cheng

Truong

Barrett

et al. 2019

ACS Sustainable Chem. Eng.

View full text Add to dashboard Cite

Lignin is the largest renewable source of aromatic chemical building blocks on the planet and has great potential for the production of value-added chemicals.Herein, we describe lignin hydrogenolysis/depolymerization of organosolv poplar lignin (OPL) in ethanol/iso-propanol solvent in the absence of added catalysts. Different EtOH/i-PrOH ratios as well as various reaction conditions were evaluated. OPL depolymerization was more effective in the mixed media than in ethanol or iso-propanol alone. Heating OPL at 270 °C for 4 h in 50:50 (v:v) EtOH/i-PrOH in a closed pressure vessel gave an overall oil yield of 70 wt% of which about 48% consisted of the monomers (E)-4-propenyl syringol and iso-eugenol. Notably, these catalyst-free reactions in ethanol/iso-propanol media show monomer yields comparable to those reported for lignin depolymerization using precious metal catalysts and dihydrogen, which suggests unexpectedly favorable H-donor ability of this mixed alcohol medium.

show abstract

Section: Discussionsupporting

confidence: 55%

Hydrogenolysis of Organosolv Lignin in Ethanol/Isopropanol Media without Added Transition-Metal Catalyst

Cheng

Truong

Barrett

et al. 2019

ACS Sustainable Chem. Eng.

View full text Add to dashboard Cite

show abstract

“…In earlier studies, supercritical methanol or ethanol was used as the reaction medium and KOH was the preferred base for the BCD step. These choices were based on the successful application of these materials to the depolymerization of low-rank coals [3][4][5][6][7][8][9][10][11][12]. Sandia's contribution to these studies is presented elsewhere [13,14,15].…”

Section: Introductionmentioning

confidence: 99%

Batch Microreactor Studies of Lignin Depolymerization by Bases. 2. Aqueous Solvents

MILLER¹,

EVANS²,

MUDD³

et al. 2002

View full text Add to dashboard Cite

Biomass feedstocks contain roughly 15-30% lignin, a substance that can not be converted to fermentable sugars. Hence, most schemes for producing biofuels assume that the lignin coproduct will be utilized as boiler fuel. Yet, the chemical structure of lignin suggests that it will make an excellent high value fuel additive, if it can be broken down into smaller compounds. From Fiscal year 1997 through Fiscal year 2001, Sandia National Laboratories participated in a cooperative effort with the National Renewable Energy Laboratory and the University of Utah to develop and scale a base catalyzed depolymerization (BCD) process for lignin conversion. SNL's primary role in the effort was to perform kinetic studies, examine the reaction chemistry, and to develop alternate BCD catalyst systems. This report summarizes the work performed at Sandia during Fiscal Year 1999 through Fiscal Year 2001 with aqueous systems. Work with alcohol based systems is summarized in part 1 of this report.Our study of lignin depolymerization by aqueous NaOH showed that the primary factor governing the extent of lignin conversion is the NaOH:lignin ratio. NaOH concentration is at best a secondary issue. The maximum lignin conversion is achieved at NaOH:lignin mole ratios of 1.5 -2. This is consistent with acidic compounds in the depolymerized lignin neutralizing the base catalyst. The addition of CaO to NaOH improves the reaction kinetics, but not the degree of lignin conversion. The combination of Na 2 CO 3 and CaO offers a cost saving alternative to NaOH that performs identically to NaOH on a per Na basis. A process where CaO is regenerated from CaCO 3 could offer further advantages, as could recovering the Na as Na 2 CO 3 or NaHCO 3 by neutralization of the product solution with CO 2 . Model compound studies show that two types of reactions involving methoxy substituents on the aromatic ring occur: methyl group migration between phenolic groups (making and breaking ether bonds) and the loss of methyl/methoxy groups from the aromatic ring (destruction of ether linkages). The migration reactions are significantly faster than the demethylation reactions, but ultimately demethylation processes predominates.

show abstract

“…Similarly, it was reported that isopropyl alcohol is converted to acetone and hydrogen gas with KOH at 335 "C [12], and it has been suggested that methanol would undergo similar reactions [ 11,171. These results suggest the higher order products in our system may have formed stepwise as follows: ethylene formation from ethanol, ethylene oligomerization, olefin hydrolysis (butanol, hexanol), alcohol oxidation (butanoic acid), esterification (upon acidification).…”

Section: Model Compound Studiesmentioning

confidence: 90%

Batch Microreactor Studies of Lignin Depolymerization by Bases. 1. Alcohol Solvents

Miller¹,

Evans²,

Mudd³

et al. 2002

View full text Add to dashboard Cite

Biomass feedstocks contain roughly 10-30% lignin, a substance that can not be converted to fermentable sugars. Hence, most schemes for producing biofuels (ethanol) assume that the lignin coproduct will be utilized as boiler fuel to provide heat and power to the process. However, the chemical structure of lignin suggests that it will make an excellent high value fuel additive, if it can be broken down into smaller molecular units. From fiscal year 1997 through fiscal year 2001, Sandia National Laboratories was a participant in a cooperative effort with the National Renewable Energy Laboratory and the University of Utah to develop and scale a base catalyzed depolymerization (BCD) process for lignin conversion. SNL's primary role in the effort was to utilize rapidly heated batch microreactors to perform kinetic studies, examine the reaction chemistry, and to develop alternate catalyst systems for the BCD process. This report summarizes the work performed at Sandia during FY97 and FY98 with alcohol based systems. More recent work with aqueous based systems will be summarized in a second report.Batch microreactor studies demonstrated that the conversion of lignin to ether solubles by KOH in methanol or ethanol was rapid at 290 "C, reaching the maximum value (only 7% ether insoluble material remaining) within 10-15 minutes. Model compound studies confirmed that the dominant depolymerization route is the solvolysis of ether linkages. Strong bases (KOH, NaOH, CsOH) were shown to convert more of the lignin to ether soluble material than weaker bases (LiOH, Ca(OH)2, and Na2C03). An excess of base relative to lignin monomer units is required for maximum conversion. However, a synergistic interaction between NaOH and Ca(OH)* allows reasonable conversions of lignin to be achieved with small amounts of NaOH by coupling it with Ca(OH)2. Ethanol and methanol are converted to acetic and formic acid respectively under the reaction conditions with an activation energy of approximately 50 kcal/mol. This results in a loss of solvent, but more importantly neutralizes the base catalyst, halting forward progress of the reaction, and accounting for the excess base requirement.3

show abstract

Alcohols as H-donor media in coal conversion. 2. Base-promoted H-donation to coal by methyl alcohol

Cited by 76 publications

References 3 publications

Hydrogenolysis of Organosolv Lignin in Ethanol/Isopropanol Media without Added Transition-Metal Catalyst

Hydrogenolysis of Organosolv Lignin in Ethanol/Isopropanol Media without Added Transition-Metal Catalyst

Batch Microreactor Studies of Lignin Depolymerization by Bases. 2. Aqueous Solvents

Batch Microreactor Studies of Lignin Depolymerization by Bases. 1. Alcohol Solvents

Contact Info

Product

Resources

About