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Catalytic conversion of syngas to ethanol and higher alcohols over Rh and Cu based catalysts
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology. UMSA-Universidad Mayor de San Andrés, Bolivia.ORCID iD: 0000-0001-8488-4429
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thermochemical process converts almost any kind of biomass to a desired final product, i.e. gaseous or liquid transportation fuels and chemicals. The transportation fuels obtained in this way are renewable biofuels, which are alternatives to fossil fuels. During the last few years, thermochemical plants for the production of bioethanol have been launched and another is under construction. A total of about 290 million liters of ethanol are expected to be processed per year, mostly using municipal solid waste. Considerable efforts have been made in order to find a more selective catalyst for the conversion of biomass-derived syngas to ethanol.

The thesis is the summary of five publications. The first two publications (Papers I and II) review the state of the art of ethanol and higher alcohols production from biomass, as well as the current status of synthetic fuels production by other processes such as the Fischer-Tropsch synthesis. Paper III analyses the catalytic performance of a mesoporous Rh/MCM-41 (MCM-41 is a hexagonal mesoporous silica) in the synthesis of ethanol which is compared to a typical Rh/SiO2 catalyst. Exhaustive catalytic testing including the addition of water vapor and modifying the hydrogen partial pressure in the syngas feed-stream which, in addition to the catalyst characterization (XRD, BET, XPS, chemisorption, TEM and TPR) before and after the catalytic testing, have allowed concluding that some water vapor can be concentrated in the pores of the Rh/MCM-41 catalyst. The concentration of water-vapor promotes the occurrence of the water gas shift reaction, which in turn induces some secondary reactions that change the product distribution, as compared to results obtained from the typical Rh/SiO2 catalyst. These results have been verified in a wide range of syngas conversion levels (1-68 %) and for different catalyst activation procedures (catalyst reduction at 200 °C, 500 °C and no-reduction) as shown in Paper IV. Finally, similar insights about the use of mesoporous catalyst have been found over a Cu/MCM-41 catalyst, shown in Paper V. Also in Paper V, the effect of metal promoters (Fe and K) has been studied; a noticeable increase of ethanol reaction rate was found over Cu-Fe-K/MCM-41 catalyst as compared to Cu/MCM-41. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. , 98 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:2
Keyword [en]
thermochemical process, ethanol, higher alcohols, mesoporous catalysts, rhodium, copper, metal promoters
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-196808ISBN: 978-91-7729-206-7 (print)OAI: oai:DiVA.org:kth-196808DiVA: diva2:1048937
Public defence
2017-01-27, Q2, Osquldas väg 10, Våning 2, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Sida - Swedish International Development Cooperation Agency
Note

QC 20161125

Available from: 2016-11-25 Created: 2016-11-22 Last updated: 2017-02-03Bibliographically approved
List of papers
1. Catalytic conversion of biomass-derived synthesis gas to fuels
Open this publication in new window or tab >>Catalytic conversion of biomass-derived synthesis gas to fuels
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2015 (English)In: Catalysis. Volume 27, Royal Society of Chemistry, 2015, 62-143 p.Chapter in book (Refereed)
Abstract [en]

Biomass-derived fuels constitute a promising alternative for diversifying the fuel supply and reducing the consumption of fossil fuels, leading to a reduction in greenhouse gas emissions and thus mitigating global warming. Biomass can be converted to synthesis gas, which can serve as a source for various liquid and gaseous fuels. Although significant progress has been achieved in the overall process, both economic and technical challenges still need to be overcome. Many pilot plants are already in operation and the first demonstration and semi-commercial installations are under construction or starting to operate. Catalysis is a key parameter in the conversion of synthesis gas to fuels. The aim of this work is to present the latest advances in the catalytic conversion of synthesis gas to Fischer-Tropsch gasoline and diesel, synthetic natural gas, ethanol and mixed alcohols. The syntheses of methanol and dimethyl ether are also briefly reviewed.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015
Series
Catalysis, ISSN 0140-0568 ; 27
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-167768 (URN)10.1039/9781782622697-00062 (DOI)2-s2.0-84926505246 (Scopus ID)978-1-78262-054-9 (ISBN)978-1-78262-269-7 (ISBN)
Funder
Sida - Swedish International Development Cooperation AgencyEU, FP7, Seventh Framework Programme, FP7/2013
Note

QC 20161123

Available from: 2015-05-27 Created: 2015-05-22 Last updated: 2017-10-04Bibliographically approved
2. Gas to liquids: A technology for natural gas industrialization in Bolivia
Open this publication in new window or tab >>Gas to liquids: A technology for natural gas industrialization in Bolivia
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2010 (English)In: Journal of Natural Gas Science and Engineering, ISSN 1875-5100, E-ISSN 2212-3865, Vol. 2, no 5, 222-228 p.Article in journal (Refereed) Published
Abstract [en]

Gas-to-Liquids (GTL) technology converts natural gas, through Fischer-Tropsch synthesis, into liquid and ultra-clean hydrocarbons such as light oils, kerosene, naphtha, diesel, and wax. Bolivia has natural gas reserves that reach 48.7 trillion cubic feet and produces nearly 40.0 million cubic meters per day, from which, around 88% are exported to Brazil and Argentina. In spite of these considerable amounts of natural gas reserves and production, the country experiences a shortage of diesel which cannot be solved using conventional refining processes due the light nature of its crude oil. Thus, the GTL process seems to be a promising solution for Bolivia's diesel problems, at the same time that its natural gas reserves could be monetized. Although GTL can be considered as a well proven and developed technology, there are several aspects along the main processing steps (synthesis gas generation, Fischer-Tropsch synthesis, and product upgrading) to be considered at the time of implementing a GTL plant. The aim of this paper is to give an overall view of some relevant issues related to Gas-to-Liquids technology as an option for natural gas industrialization in Bolivia, and also to provide a landscape of Bolivian natural gas industry.

Keyword
Bolivian natural gas, Gas-to-Liquids (GTL), Synthesis Gas, Fischer-Tropsch, Hydrocracking
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-138474 (URN)10.1016/j.jngse.2010.10.001 (DOI)000208679200003 ()2-s2.0-78049504771 (Scopus ID)
Note

QC 20140109

Available from: 2014-01-09 Created: 2013-12-19 Last updated: 2016-11-23Bibliographically approved
3. Synthesis of Ethanol from Syngas over Rh/MCM-41 Catalyst: Effect of Water on Product Selectivity
Open this publication in new window or tab >>Synthesis of Ethanol from Syngas over Rh/MCM-41 Catalyst: Effect of Water on Product Selectivity
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2015 (English)In: CATALYSTS, ISSN 2073-4344, Vol. 5, 1737-1755 p.Article in journal (Refereed) Published
Abstract [en]

The thermochemical processing of biomass is an alternative route for the manufacture of fuel-grade ethanol, in which the catalytic conversion of syngas to ethanol is a key step. The search for novel catalyst formulations, active sites and types of support is of current interest. In this work, the catalytic performance of an Rh/MCM-41 catalyst has been evaluated and compared with a typical Rh/SiO2 catalyst. They have been compared at identical reaction conditions (280 degrees C and 20 bar), at low syngas conversion (2.8%) and at same metal dispersion (H/Rh = 22%). Under these conditions, the catalysts showed different product selectivities. The differences have been attributed to the concentration of water vapor in the pores of Rh/MCM-41. The concentration of water vapor could promote the water-gas-shift-reaction generating some extra carbon dioxide and hydrogen, which in turn can induce side reactions and change the product selectivity. The extra hydrogen generated could facilitate the hydrogenation of a C-2-oxygenated intermediate to ethanol, thus resulting in a higher ethanol selectivity over the Rh/MCM-41 catalyst as compared to the typical Rh/SiO2 catalyst; 24% and 8%, respectively. The catalysts have been characterized, before and after reaction, by N-2-physisorption, X-ray photoelectron spectroscopy, X-ray diffraction, H-2-chemisorption, transmission electron microscopy and temperature programmed reduction.

Place, publisher, year, edition, pages
MDPI AG, 2015
Keyword
ethanol, syngas, Rh/MCM-41 catalyst, water vapor
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-180993 (URN)10.3390/catal5041737 (DOI)000367535300008 ()2-s2.0-84944885472 (Scopus ID)
Funder
Sida - Swedish International Development Cooperation Agency
Note

QC 20160127

Available from: 2016-01-27 Created: 2016-01-26 Last updated: 2016-11-24Bibliographically approved
4. Effect of syngas conversion and catalyst reduction temperature in the synthesis of ethanol: concentration of water vapor in mesoporous Rh/MCM-41 catalyst
Open this publication in new window or tab >>Effect of syngas conversion and catalyst reduction temperature in the synthesis of ethanol: concentration of water vapor in mesoporous Rh/MCM-41 catalyst
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2015 (English)In: Catalysis communications, ISSN 1566-7367, E-ISSN 1873-3905, Vol. 69, 183-187 p.Article in journal (Refereed) Published
Abstract [en]

Rh-based catalysts typically show low selectivity to CO2 in the synthesis of ethanol from syngas. However, a novel mesoporous Rh/MCM-41 catalyst shows high selectivity to CO2 in a large range of syngas conversions; 1% to 68%, regulated by adjusting the operation conditions (270-430 degrees C, 30-90 bar and 6000-40,000 ml(syngas)/gcat h). The same effect is obtained at different catalyst reduction temperatures (200 degrees C and 500 degrees C) as well as on the non-reduced catalyst. A high concentration of water vapor seems to occur in the pores of Rh/MCM-41 which may promote the water-gas-shift-reaction, producing extra CO2 and H-2. (C) 2015 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Ethanol, Reduction temperature, Rh/MCM-41, Syngas conversion
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-173417 (URN)10.1016/j.catcom.2015.06.015 (DOI)000359885900039 ()2-s2.0-84934278111 (Scopus ID)
Funder
Sida - Swedish International Development Cooperation Agency
Note

QC 20150915

Available from: 2015-09-15 Created: 2015-09-11 Last updated: 2016-11-24Bibliographically approved
5. Syngas conversion to ethanol over a mesoporous Cu/MCM-41 catalyst: Effect of K and Fe promoters
Open this publication in new window or tab >>Syngas conversion to ethanol over a mesoporous Cu/MCM-41 catalyst: Effect of K and Fe promoters
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2016 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 526, 77-83 p.Article in journal (Refereed) Published
Abstract [en]

Transportation fuels such as ethanol can be obtained through thermochemical processing of biomass. Interest in the development of more selective catalysts for the conversion of biomass-derived syngas (H2 + CO) to ethanol is increasing in both academia and industry. In this work, we have evaluated the performances of K and Fe as metal promoters of a mesoporous Cu/MCM-41 catalyst and their effects on the product selectivity and especially on ethanol formation. The metal loading was 29 wt.% Cu, 2 wt.% Fe and 1.6 wt.% K. The catalysts were tested at 300 °C, 20 bar and gas-hourly-space-velocities in the range of 1500–30000 mlsyngas/gcat h; under these conditions the syngas conversion level was between 2 and 11%. The non-promoted Cu/MCM-41 catalyst showed interesting selectivity toward oxygenated compounds, mostly methanol. The addition of K as promoter increases the selectivity toward methanol even more, while the addition of Fe as promoter favors the formation of hydrocarbon compounds. When both K and Fe as promoters are incorporated into the Cu/MCM-41 catalyst, the reaction rate to oxygenated compounds is notably increased, especially for ethanol. The space time yield for ethanol for the Cu/MCM-41 catalyst is 0.3 × 10−5 carbon-mol/gcath which increases to 165.5 × 10−5 carbon-mol/gcath for the Cu-Fe-K/MCM-41 catalyst. From XPS analysis, the Cu-Fe-K/MCM-41 catalyst was found to have the following atomic composition: Cu0.34Fe0.08K0.08Si1.00. The promoting effect of both K and Fe, may be related to an increased reaction rate toward CO non-dissociation and CO-dissociation paths, respectively, which is beneficial for the ethanol formation. Further catalytic results, catalyst characterization and discussion of results are presented in this work.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
Copper, Ethanol, Mesoporous MCM-41, Promoters, Syngas, Catalysts, Copper compounds, Dissociation, Ethanol fuels, Hydrocarbon refining, Iron compounds, Mesoporous materials, Methanol, Reaction rates, Synthesis gas, Catalyst characterization, Gas hourly space velocities, Hydrocarbon compounds, Product selectivities, Syn-gas, Thermochemical processing, Catalyst selectivity
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-195315 (URN)10.1016/j.apcata.2016.08.006 (DOI)000384865600010 ()2-s2.0-84981263991 (Scopus ID)
Note

QC 20161110

Available from: 2016-11-10 Created: 2016-11-02 Last updated: 2016-11-25Bibliographically approved

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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
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  • nn-NO
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Output format
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