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The present thesis concerns catalytic conversion of syngas (H2+ CO) into a blend of methanol and higher alcohols, an attractive way of producing fuels and chemicals. This route has the potential to reduce the oil dependence in the transport sector and, with the use of biomass for the syngas generation, produce CO2-neutral fuels. Alkali promoted MoS2-based catalysts show a high selectivity to higher alcohols, while at the same time being coke resistant, sulfur tolerant and displaying high water-gas shift activity. This makes this type of catalyst especially suitable for being used with syngas derived from biomass or coal which typically has a low H2/CO-ratio. This thesis discusses various important aspects of higher alcohol synthesis using MoS2-based catalysts and is a summary of four scientific papers. The first part of the thesis gives an introduction to how syngas can be produced and converted into different fuels and chemicals. It is followed by an overview of higher alcohol synthesis and a description of MoS2-based catalysts. The topic alcohol for use in internal combustion engines ends the first part of the thesis. In the second part, the experimental part, the preparation of the MoS2-based catalysts and the characterization of them are handled. After describing the high-pressure alcohol reactor setup, the development of an on-line gas chromatographic system for higher alcohol synthesis with MoS2 catalysts is covered (Paper I). This method makes activity and selectivity studies of higher alcohol synthesis catalysts more accurate and detailed but also faster and easier. Virtually all products are very well separated and the established carbon material balance over the reactor closed well under all tested conditions. The method of trace level sulfur analysis is additionally described. Then the effect of operating conditions, space velocity and temperature on product distribution is highlighted (Paper II). It is shown that product selectivity is closely correlated with the CO conversion level and why it is difficult to combine both a high single pass conversion and high alcohol selectivity over this catalyst type. Correlations between formed products and formation pathways are additionally described and discussed. The CO2 pressure in the reactor increases as the CO conversion increases, however, CO2 influence on formation rates and product distribution is to a great extent unclear. By using a CO2-containing syngas feed the effect of CO2 was studied (Paper III). An often emphasized asset of MoS2-based catalysts is their sulfur tolerance. However, the use of sulfur-containing feed and/or catalyst potentially can lead to incorporation of unwanted organic sulfur compounds in the product. The last topic in this thesis covers the sulfur compounds produced and how their quantity is changed when the feed syngas contains H2S (Paper IV). The effect on catalyst activity and selectivity in the presence of H2S in the feed is also covered. / <p>QC 20150115</p>

Thesis (MScEng)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Pure primary alcohols are very valuable as raw materials and solvents. Close-boiling alcohol mixtures are produced as byproducts from the Fischer Tropsch synthesis. These byproducts include the mixtures 1-butanol+2- penta noI and 1-pentanol+2-hexanol. Due to the small difference in boiling points these alcohols cannot be separated from one another by using conventional distillation. This study has been undertaken to determine whether primary and secondary alcohols may be separated by exploitation of their chemical properties. Esterification of the alcohols followed by distillation of the esters into cuts and hydrolyses of the esters, has been attempted to separate the alcohols. This however, was unsuccessful. In this study the difference in dehydration rate of secondary and primary alcohols in acidic media has also been investigated. Several acidic resins and liquid catalysts have been used. The acidic resins gave no dehydration or extremely low dehydration rates in the liquid phase. The liquid catalysts H2S04, Oxalic Acid, NaHS04 and H3P04 were investigated. H3P04 gave excellent results. Laboratory experiments were conducted at the boiling point of the reaction mixture at atmospheric pressure. The reaction mixture was sampled at varying time intervals and analysed. The secondary alcohol dehydrated rapidly to the corresponding alkene. The primary alcohol formed symmetrical ethers at a very low rate. The primary and secondary alcohol also combined to form small amounts of unsymmetrical ethers. After the dehydration reaction the organic products can be separated from the acid with a'short path distillation unit. The primary alcohol can further be purified by conventional distillation. Conceptual process designs were done for the separation and purification of the reactor product streams of the alcohol mixtures 1-butanol+2-pentanol and 1-pentanol+2-hexanol. n laboratory scale it was found that for the separation of 85% 1-butanol and 15% 2-pentanol (mass %), 90 % H3P04 (mass %) at an acid:alcohol ratio of 1,5: 1 results in suffcient dehydration of 2-pentanol. A reaction time of 70 minutes is required. A conceptual design on the purification of the 1-butanol predicted a product quality of 99,5 % 1-butanol (mass %) and a 1-butanol recovery of 75 %. The 1-butanol recovery is low, because a major part of the 1-butanol is lost in the purification as part of the ternary azeotrope with water and n-butylether. On laboratory scale it was also found that for the separation of 85 % 1- pentanol+15 % 2-hexanol (mass %),90 % H3P04 (mass %) at an acid:alcohol ratio of 1,5:1 gives sufficient dehydration of 2-hexanol. A reaction time of only 35 minutes is required. A conceptual design on the purification of the 1- pentanol predicted a product quality of 99,9 % 1-pentanol and a 1-pentanol recovery of > 98 %. The 1-pentanol recovery is excellent, only the 1- pentanol that is converted to ethers is lost. In this study it has been proven that a dehydration separation process can be applied successfully to remove secondary alcohols from a primary+secondary alcohol mixture. Especially the removal of 2-hexanol from a 1-pentanol+2- hexanol mixture gave promising results. In order to assess the economic viability of this dehydration process an economic evaluation should be done. This could be part of subsequent studies. The dehydration separation process should be investigated further. It is believed that this dehydration separation process can be expanded to higher alcohols, e.g. 1-hexanol+2-heptanol. It would be extremely advantageous if a solid catalyst could be found for the separation. In this case the recovery of the organics from the reaction mixture would be very much easier. If a solid catatyst is not found, a continuous process using H3P04 as liquid catalyst should be developed. / AFRIKAANSE OPSOMMING: Suiwer primêre alkohole is baie waardevolle rou materiale en oplosmiddels. Alkohol mengsels, wat uit naby-kokende alkohole bestaan, word as neweprodukte in die Fischer Tropsch Sintese gevorm. Hierdie newe-produkte sluit alkohol mengsels soos 1-butanol+2-pentanol en 1-pentanol+2-hexanol in. Weens die klein verskil in kookpunte van hierdie alkohole kan die alkohole nie met konvensionele distillasie van mekaar geskei word nie. Hierdie studie is onderneem om te bepaal of die chemiese eienskappe van alkohole benut kan word om primêre en sekondêre alkohole van mekaar te skei. 'n Poging is aangewend om die alkohole met behulp van esterifikasie te skei. Die alkohole is eers ge-esterifiseer, daarna met behulp van distillasie in verskeie snitte verdeel en die alkohol is vrygestel deur hidrolise van die esters. Dit was egter onsuksesvol. Die verskil in dehidrasie tempo van sekondêre en primêre alkohole in suur mediums is ook ondersoek. Verskeie suur harse en vloeibare kataliste is ondersoek. Die suur .harse het of geen dehidrasie of baie lae dehidrasie tempo's in die vloeistoffase gegee. Die vloeistof kataliste H2S04, Oksaalsuur, NaHS04 en H3P04 is ondersoek. H3P04 het uitstekende resultate gelewer. Eksperimente is op laboratoriumskaal en onder atmosferiese druk uitgevoer. Monsters is van die reaksiemengsels by verskillende tydsintervalle geneem en geanaliseer. Die sekondêre alkohol het vinnig na die ooreenstemmende alkeen gedehidreer. Die primêre alkohole het simmetriese eters teen 'n lae tempo gevorm. Die primêre en sekondêre alkohole het ook gekombineer om gemengde eters te vorm. Kort-pad-distillasie kan gebruik word om na die dehidrase reaksie die organiese produkte van die suur te verwyder. Die primêre alkohole kan verder met konvensionele distillasie gesuiwer word. Konseptueie prosesontwerpe is uitgevoer vir die skeiding en suiwering van die alkohol mengsels 1-butanol+2-pentanol en 1-pentanol+2-hexanol nadat dehidrasie van die mengsels uitgevoer is. Op laboratoriumskaal is dit gevind dat vir die skeiding van 85% 1-butanol en 15% 2-pentanol (massa %), 90 % H3P04 (massa %) met 'n suur:alkohol verhouding van 1,5:1 effektiewe dehidrase van 2-pentanol lewer. fn Reaksietyd van 70 minute word benodig. fn Konseptueie ontwerp vir die suiwering van die 1-butanol het fn produkkwaliteit van 99,5 % 1-butanol (massa %) en fn 1-butanol opbrengs van 75 % voorspel. Die 1-butanol opbrengs is laag aangesien fn groot deel van die 1-butanol verlore gaan as deel van die ternêre azeotroop wat 1-butanol met n-butieleter en water vorm. Dit is ook op laboratoriumskaal vasgestel dat vir die skeiding van 85 % 1- pentanol+15 % 2-hexanol (massa %), 90 % H3P04 (massa %) met fn suur:alkohol verhouding van 1,5:1 effektiewe dehidrase van 2-hexanollewer. fn Reaksietyd van slegs 35 minute word benodig. fn Konseptueie ontwerp vir die suiwering van die 1-pentanol het fn produkkwaliteit van 99,9 % 1-pentanol en fn 1-pentanol opbrengs van > 98 % voorspel. Die 1-pentanol opbrengs is uitstekend, en slegs die 1-pentanol wat omgeskakel word na eters gaan verlore. In hierdie studie is dit bewys dat fn dehidrasie skeidingsproses suksevol aangewend kan word om sekondêre alkohole uit fn primêre+sekondêre alkohol mengsel te verwyder. Veral die verwydering van 2-hexanol uit fn 1- pentanol+2-hexanol mengsel het belowende resultate gelewer. Om die ekonomiese lewensvatbaarheid van so fn skeidingsproses te bepaal moet fn ekonomiese evaluasie van die proses gedoen word. Dit behoort deel van verdere studies te vorm. Die dehidrasie skeidingsproses behoort verder ondersoek te word. Dit word verwag dat die proses na hoër alkohol mengsels, bv. 1-hexanol+2-heptanol uitgebrei kan word. Dit sou baie voordelig wees indien fn geskikte soliede katalis vir die skeiding gevind word. In so fn geval sou die herwinning van die organiese produkte van die reaksiemengsel baie makliker wees. Indien fn soliede katalis nie gevind word nie, behoort fn kontinu proses waarin H3P04 as vloeistof katalis gebruik word, ontwikkel te word.

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Thesis advisor: James P. Morken / The metal-catalyzed diboration of alkenes has gained fame as a practical methodology for use in the stereoselective construction of complex organic molecules and synthetic building blocks. The created carbon-boron bonds have tremendous versatility and can easily be manipulated into carbon-carbon or carbon-heteroatom bonds. Unfortunately, metal-catalyzed diborations often suffer from limitations such as substrate specificity. To address these issues, we investigated diboration reactions in the absence of transition-metal catalysts. Herein is presented a transition-metal-free, diastereoselective diboration methodology utilizing alkenyl alcohols as substrates. Allylic alcohols can be treated with an organolithium base and bis(pinacolato)diboron to generate 1,2,3-triols upon oxidation. Most studies were done on homoallylic alcohols, which can be performed using a carbonate base and an alcohol additive. This methodology has many strengths, such as a wide substrate scope and high levels of diastereoselectivity. Further investigations into product functionalization and synthetic applications will be pursued in due time. / Thesis (MS) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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Thesis (M.S.)--Mississippi State University. Department of Chemical Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Ohio State University, 1924. / Includes bibliographical references. Available online via OhioLINK's ETD Center