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Synthesis, performance and regeneration of carbon membranes for biogas upgrading - a future energy carrier

Abstract

The focus of the current work was to find a low-cost precursor for carbon molecular sieve (CMS) membranes for biogas upgrading (i.e. CO{sub 2}/CH{sub 4} separation to meet vehicle fuel criteria), and a simple way of producing them. Wood pulp from spruce and pine containing a majority of cellulose resulted in carbons with CO{sub 2}/CH{sub 4} separation performance at the same level as those derived from specialty polymers like polyimides. Pulp has the advantage of being widespread and cheap. Cellulose hydrolysis with trifluoroacetic acid (TFA), that is gentle enough to preserve the monosaccharides, provided an anticipative route to carbon membrane formation. Increasing the hydrolysis time, resulted in reduced weight loss during carbonization, and better separation performance for the gas pair CO{sub 2}/CH{sub 4}. The results indicated that furans are a key intermediate in forming microporosity with high separation performance. For the separation of CO2 from CH{sub 4} the optimum carbon formation temperature seemed to be near 650{sup d}eg C (single gas tests at 30{sup d}eg C and 2 bar feed pressure). In addition, several ways of modifying a carbon material are described. The modification method used in this study was metal doping of carbon. CMS membranes were formed by vacuum  More>>
Authors:
Publication Date:
Jul 01, 2005
Product Type:
Thesis/Dissertation
Report Number:
NEI-NO-1554
Reference Number:
RN05145263; TVI: 0520
Resource Relation:
Other Information: TH: Thesis (Dr Ing); 15 appendices, 121 figs., 335 refs., 67 tabs
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 03 NATURAL GAS; MEMBRANES; REGENERATION; CARBON; SYNTHESIS; PERFORMANCE TESTING; EVALUATED DATA; EXPERIMENTAL DATA; METHANE; PURIFICATION; HYDROLYSIS; CARBON DIOXIDE; CARBONIZATION; MATERIALS; MODIFICATIONS; METALS; CHEMICAL PREPARATION; COMPARATIVE EVALUATIONS; FEASIBILITY STUDIES; NATURAL GAS; CHEMISTRY
OSTI ID:
20656603
Research Organizations:
Norges teknisk-naturvitenskapelige universitet, Trondheim (Norway)
Country of Origin:
Norway
Language:
English
Other Identifying Numbers:
Other: ISBN 82-471-7192-9; TRN: NO0505486
Availability:
Commercial reproduction prohibited; OSTI as DE20656603
Submitting Site:
NW
Size:
vp.
Announcement Date:
Dec 05, 2005

Citation Formats

Lie, Jon Arvid. Synthesis, performance and regeneration of carbon membranes for biogas upgrading - a future energy carrier. Norway: N. p., 2005. Web.
Lie, Jon Arvid. Synthesis, performance and regeneration of carbon membranes for biogas upgrading - a future energy carrier. Norway.
Lie, Jon Arvid. 2005. "Synthesis, performance and regeneration of carbon membranes for biogas upgrading - a future energy carrier." Norway.
@misc{etde_20656603,
title = {Synthesis, performance and regeneration of carbon membranes for biogas upgrading - a future energy carrier}
author = {Lie, Jon Arvid}
abstractNote = {The focus of the current work was to find a low-cost precursor for carbon molecular sieve (CMS) membranes for biogas upgrading (i.e. CO{sub 2}/CH{sub 4} separation to meet vehicle fuel criteria), and a simple way of producing them. Wood pulp from spruce and pine containing a majority of cellulose resulted in carbons with CO{sub 2}/CH{sub 4} separation performance at the same level as those derived from specialty polymers like polyimides. Pulp has the advantage of being widespread and cheap. Cellulose hydrolysis with trifluoroacetic acid (TFA), that is gentle enough to preserve the monosaccharides, provided an anticipative route to carbon membrane formation. Increasing the hydrolysis time, resulted in reduced weight loss during carbonization, and better separation performance for the gas pair CO{sub 2}/CH{sub 4}. The results indicated that furans are a key intermediate in forming microporosity with high separation performance. For the separation of CO2 from CH{sub 4} the optimum carbon formation temperature seemed to be near 650{sup d}eg C (single gas tests at 30{sup d}eg C and 2 bar feed pressure). In addition, several ways of modifying a carbon material are described. The modification method used in this study was metal doping of carbon. CMS membranes were formed by vacuum carbonization of hydrolyzed cellulose and metal loaded hydrolyzed cellulose. Metal additives include oxides of Ca, Mg, Fe(III) and Si, and nitrates of Ag, Cu and Fe(III). The carbon membrane containing Fe-nitrate has promising separation performance for the gas pairs 02/N2 and CO{sub 2}/CH{sub 4}. The CO{sub 2}/CH{sub 4} selectivity was typically larger than 100, with a CO2 permeability of about 300 Barrer (single gas tests). Carbon containing nitrates of Cu or Ag showed high selectivity, but reduced 02 and CO2 permeability compared to carbon with Fe-nitrate. Element analysis indicated that Cu migrates to the carbon surface, creating an extra layer resistance to gas transport. A silver mirror was also seen on the surface of Ag-nitrate containing carbon. However, the Ag- and Cu-containing membranes showed a high H2 permeability. Adding metal oxides makes the carbon membranes retard the transport of easily condensable gases (e.g. CO2). This can be exploited for enhanced H2/CO{sub 2} separation efficiency. A simple, energy effective and rapid regeneration method for membranes that are conductors or semi-conductors has been developed: When a low voltage, direct current was applied on an iron-doped carbon, sorption of gases in the carbon decreased, while diffusivity increased to a larger degree, resulting in enhanced permeation rates. Electrothermal regeneration may also be applied online, and is especially suitable for separation in non-oxidizing atmospheres, like CO{sub 2}/CH{sub 4} separation. The method can be used for a continuous process, and not only for batchwise regeneration (e.g. activated carbon). The CO{sub 2} permeability increased with about 60%, while the CH{sub 4} permeability was unchanged (single gas tests). Mixed gas tests on the same type of iron-doped carbon (without current applied) resulted in a reduction of both the CO2 permeability and the selectivity, compared to single gas tests. High performance carbon membranes were also formed from the commercial polymer XP (cover name). The CO{sub 2}/CH{sub 4} selectivity was typically larger than 100, with a CO2 permeability of about 200 Barrer (single gas tests). The applied precursor film thickness was in the range 50-70 micron, and was found to be crucial for the carbonization process. Films of 100 microns or more resulted in cracks during carbonization, probably because of low gas drainage, and were rendered useless. Carbon membranes from XP possess two important advantages: 1) The films produced at 500 C have some degree of flexibility, hence easy to handle and process. Masking and testing these carbons were not challenging, when a proper precursor film thickness was used. 2) Aging seems not to be an issue. During the permeation tests, i.e. one week of testing, the permeability in fact increased. (Author)}
place = {Norway}
year = {2005}
month = {Jul}
}