Sökning: "Acid catalyst"

Visar resultat 1 - 5 av 147 avhandlingar innehållade orden Acid catalyst.

  1. 1. Evaluation of Pretreatment and Process Configurations for Combined Ethanol and Biogas Production from Lignocellulosic Biomass

    Författare :Pia-Maria Bondesson; Avdelningen för kemiteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Ethanol; biogas; lignocellulose; steam pretreatment; acid catalyst; acetic acid; phosphoric acid; sulphuric acid; xylose fermentation; co-fermentation; process design; SSCF;

    Sammanfattning : In view of global climate change and the increasing energy demand there is a need for renewable energy resources. This thesis discusses an energy-driven biorefinery concept based on the agricultural residues corn stover and wheat straw. The work is divided into two main parts. LÄS MER

  2. 2. Aspects on the Regio and Stereo Selectivity in the Hydrolsilylation of 1,3-Dienes

    Författare :Magnus Gustafsson; Centrum för analys och syntes; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Metallorganisk kemi; Organometallic chemistry; Organisk kemi; Organic chemistry; Lewis acid; electrophilic ring closure; asymmetric hydrosilylation; reaction conditions; isoprene; regioselectivity; oxygen; Wilkinsons catalyst; 15N-1H-HMQC; 31P; heterobidentate ligands; catalyst; palladium; epoxy-allylsilanes; rhodium complexes; dienes;

    Sammanfattning : This thesis is a summary of four papers concerning various aspects on the transition metal catalysed hydrosilylation of 1,3-dienes. The hydrosilylation reaction is formally an addition of a hydrosilane to an unsaturated system and depending on the reaction conditions, control of stereo-, regio-, and chemo-selectivity can be achieved. LÄS MER

  3. 3. Formic and Levulinic Acid from Cellulose via Heterogeneous Catalysis

    Författare :Johan Ahlkvist; Jyri-Pekka Mikkola; Riitta Keiski; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Levulinic acid; formic acid; Amberlyst 70;

    Sammanfattning : The chemical industry of today is under increased pressure to develop novel green materials, bio-fuels as well as sustainable chemicals for the chemical industry. Indeed, the endeavour is to move towards more eco-friendly cost efficient production processes and technologies and chemical transformation of renewables has a central role considering the future sustainable supply of chemicals and energy needed for societies. LÄS MER

  4. 4. Asymmetric transfer hydrogenation of ketones : Catalyst development and mechanistic investigation

    Författare :Katrin Ahlford; Hans Adolfsson; Martin Wills; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Asymmetric catalysis; reduction; amino acid; rhodium; mechanistic investigation; kinetic study; Organic chemistry; Organisk kemi; organisk kemi; Organic Chemistry;

    Sammanfattning : The development of ligands derived from natural amino acids for asymmetric transfer hydrogenation (ATH) of prochiral ketones is described herein. In the first part, reductions performed in alcoholic media are examined, where it is found that amino acid-derived hydroxamic acids and thioamides, respectively, are simple and versatile ligands that in combination with [RhCp*Cl2]2 efficiently catalyze this particular transformation. LÄS MER

  5. 5. Asymmetric Formation and Isomerization of Three-Membered Rings : Catalyst Development and Evaluation

    Författare :Sophie Bertilsson; Tobias Rein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; allylic alcohol; α-amino acid derivative; aza-Diels-Alder reaction; aziridination; cyclopropanation; desymmetrization; epoxide rearrangement; kinetic resolution; lithium amide; rhodium-carboxylate; Kemi; Chemistry; Kemi; organisk kemi; Organic Chemistry;

    Sammanfattning : Enantiopure α-amino acid derivatives were prepared using a protocol which allows for highly controlled regio- and chemoselectivity in the hydrogenation/ hydrogenolysis of aza-Diels-Alder adducts. One of the resulting α-amino esters, (1S,3R,4R)-2-azabicyclo[2.2.1]heptane-3-carboxylic acid ethyl ester, was utilized further as a catalyst precursor. LÄS MER