In view of the diminishing oil resources and the ongoing climate change, the use of efficient and environmentally benign technologies for the utilization of renewable resources has become indispensible. Therein, hydrogenolysis reactions offer a promising possibility for future biorefinery concepts. These reactions result in the cleavage of C-C and C-O bonds by hydrogen and allow direct access to valuable platform chemicals already integrated in today's value chains. Thus, hydrogenolysis bears the potential to bridge currently available technologies and future biomass-based refinery concepts. This Review highlights past and present developments in this field, with special emphasis on the direct utilization of cellulosic feedstocks.

Hydrogenolysis Goes Bio: From Carbohydrates and Sugar Alcohols to Platform Chemicals

Angesichts begrenzter Reserven fossiler Rohstoffe und einem Voranschreiten des Klimawandels werden effiziente und umweltfreundliche Technologien zur Nutzbarmachung erneuerbarer Rohstoffe unerlasslich. Dabei stellt die Hydrogenolyse eine vielversprechende Reaktion fur zukunftige Bioraffineriekonzepte dar. Sie resultiert in einer C-C- und C-O-Bindungsspaltung mit Wasserstoff und erlaubt einen direkten Zugang zu nutzlichen Plattformchemikalien, die bereits heute Teil der Wertschopfungsketten der chemischen Industrie sind. Aus diesem Grund birgt die Hydrogenolyse das Potential, existierende Wertschopfungsketten und zukunftige Bioraffineriekonzepte zu verbinden. Dieser Aufsatz stellt vorausgegangene und aktuelle Entwicklungen in diesem Bereich mit besonderem Augenmerk auf der direkten Umsetzung von Cellulose als Rohstoffe dar.

Hydrogenolyse goes Bio: Von Kohlenhydraten und Zuckeralkoholen zu Plattformchemikalien

The depolymerization of cellulose is carried out in the ionic liquid 1-butyl-3-methylimidazolium chloride in the presence of hydrogen gas. First, the ketal 1,1-diethoxycyclohexane and cellobiose were used as model substrates. For the depolymerization of cellulose itself, the combination of a heterogeneous metal catalyst and a homogeneous ruthenium catalyst proved effective. One of the possible roles of the ruthenium compound is to enhance the transfer of hydrogen to the metallic surface. The cellulose is fully converted under relatively mild conditions, with sorbitol as the dominant product in 51–74 % yield.

Reductive Splitting of Cellulose in the Ionic Liquid 1-Butyl-3-Methylimidazolium Chloride

A process for the production of a lower polyhydric alcohol or a mixture thereof by the hydrogenation and hydrolysis of a carbohydrate. The first stage hydrogenation produces higher polyhydric alcohols, such as sorbitol. In the second stage these higher polyhydric alcohols are selectively converted under the appropriate reaction conditions to lower polyhydric alcohols, such as ethylene glycol and 1,2-propylene glycol, using a sulfide-modified ruthenium catalyst.

Two stage hydrogenolysis of carbohydrate to glycols using sulfide modified ruthenium catalyst in second stage

A process for the separation of mannose is disclosed which comprises the selective adsorption of same on certain types of zeolitic molecular sieves. The process is especially useful for separating mannose from glucose epimerization product or plant tissue hydrolyzate, using zeolites selected from the group consisting of BaX, BaY, SrY, NaY and CaY.

Separation of mannose by selective adsorption on zeolitic molecular sieves

Sugar mixtures comprising glucose and either mannose, or both, are catalytically hydrogenated in aqueous solution containing 0.2-1.5% by weight (based on sugar) of sodium carbonate or other basic reacting alkali metal salt, yielding mannitol-rich solutions of sorbitol and mannitol. Hydrogenation is preferably carried out in two stages, the first at temperature of about 60°-100° C., the second at temperatures of about 110°-160° C.

High mannitol process (alkaline hydrogenation in presence of alkali metal carbonate)

Mannitol-rich aqueous solutions of sorbitol and mannitol are prepared by a process which includes (1) epimerizing glucose in aqueous solution to obtain an epimerizate containing approximately 30 percent mannose and 70 percent glucose on the dry basis, (2) contacting this glucose-mannose epimerizate with a glucose isomerase enzyme to produce a glucose-fructose-mannose solution, and (3) hydrogenating this glucose-fructose-mannose solution to produce an aqueous solution of sorbitol and mannitol.

High mannitol process (enzymatic isomerization)

A method for the synthesis of L-gulonic acid by catalytically hydrogenating D-glucuronic acid utilizing a ruthenium-based catalyst.

Ruthenium catalyzed hydrogenation of D-glucuronic acid

4,4'-biphenol and tert-alkyl substituted alkyl benzene derivatives are produced by hydrogenating a tetraalkyl diphenoquinone in an alkyl benzene solvent solution under relatively mild conditions in the presence of a heterogeneous catalyst, removing said catalyst from the resultant tetraalkyl biphenol and thereafter heating said alkyl benzene solvent solution in the presence of a strong acid catalyst to form relatively pure biphenol in high yields and a para substituted alkyl benzene derivative.

High yield process for preparing 4,4'-biphenol and para-alkylbenzenes

Biphenol and para substituted alkyl benzene derivatives are produced in high yield and purity by heating alkyl benzene solvent solutions of tetraalkyl substituted 4,4'-biphenols in the presence of strong acid catalyst.

Walter M. Kruse

Papers

High mannitol process (alkaline hydrogenation in presence of alkali metal carbonate)

High mannitol process (enzymatic isomerization)

Ruthenium catalyzed hydrogenation of D-glucuronic acid

High yield process for preparing 4,4'-biphenol and para-alkylbenzenes

High yield process for preparing 4,4'-biphenol and tert-alkylated-alkylbenzenes