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µHDS system for desulfurization of logistic fuels for fuel cell applications

Karstensson, Johan LU and Jönsson, Nicklas LU (2016) KET920 20161
Chemical Engineering (M.Sc.Eng.)
Abstract
Logistic fuels such as diesel and petrol, in which Jet A1 is included, are sulfur-containing fuels used for transports. The main problem with logistic fuels, when used in fuel cell (FC) applications, is their relatively high concentration of sulfur compounds. The sulfur compounds might poison the catalysts in all of the downstream processes, including the FC itself.

Hydrodesulfurization (HDS) is an industrial approach for effective desulfurization of fuels by converting complicated organic sulfur compounds into hydrocarbons and hydrogen sulfide (H2S), which in turn can be trapped in an adsorption cartridge. This thesis focused on a miniaturization of said technology, i.e. a µHDS-system for logistic fuels, in small-scale fuel cell... (More)
Logistic fuels such as diesel and petrol, in which Jet A1 is included, are sulfur-containing fuels used for transports. The main problem with logistic fuels, when used in fuel cell (FC) applications, is their relatively high concentration of sulfur compounds. The sulfur compounds might poison the catalysts in all of the downstream processes, including the FC itself.

Hydrodesulfurization (HDS) is an industrial approach for effective desulfurization of fuels by converting complicated organic sulfur compounds into hydrocarbons and hydrogen sulfide (H2S), which in turn can be trapped in an adsorption cartridge. This thesis focused on a miniaturization of said technology, i.e. a µHDS-system for logistic fuels, in small-scale fuel cell systems.

The goal was to desulfurize Jet A1 for utilization in FC-applications. Through investigation and evaluation of different catalysts and process parameters, a catalytic reactor system was developed. Desirable was to achieve a sulfur level below 10 ppm which is low enough for injection into a FC.

The approach was to set up a micro-scale plug flow reactor (PFR) in which the effects of temperature (260 °C – 450 °C), pressure (2 bar – 8 bar) and LHSV (1 h-1 – 4 h-1), on catalytic activity, was investigated. Incipient wetness impregnation was used for the preparation of six different catalysts, which were tested in said reactor. Detailed investigations were done on a Pt/alumina (PPt-47, manufactured by Stonemill AB) catalyst as well as on a CoMo/alumina catalyst impregnated with citric acid (CA). Their activity was determined based on the conversion of thiophene and dibenzothiophene (DBT). As a final test, Jet A1 was desulfurized using the same two catalysts.

CoMo-CA was consistently the better performing catalyst compared with PPt-47, reaching a sulfur conversion of 98.2 %, compared to 93.2 % when tested with Jet A1 at the most severe reactor settings. A sulfur level of 13.3 ppm was achieved with the CoMo-CA, applicable in a high-temperature FC. (Less)
Popular Abstract (Swedish)
Bränsleceller är ett intressant alternativ till förbränningsmotorer då bränsleceller har en högre effektivitet, är miljövänligare samt tystare.

Bränslen som diesel, bensin samt det undersökta bränslet Jet A1, innehåller olika svårreagerade svavelföreningar. Problemet med bränslena är att de har ett relativt högt svavelinnehåll. Svavelföreningarna riskerar att förgifta katalysatorerna i de nedströms kommande processerna, inklusive bränslecellen själv, och måste därför avsvavlas.

Genom att omvandla komplicerade svavelföreningar till vätesulfid, som i sin tur tillfångatas i en adsorptionspatron, är väteavsvavling ett effektivt industriellt tillvägagångssätt att avsvavla på.

Syftet med detta examensarbete har varit att undersöka... (More)
Bränsleceller är ett intressant alternativ till förbränningsmotorer då bränsleceller har en högre effektivitet, är miljövänligare samt tystare.

Bränslen som diesel, bensin samt det undersökta bränslet Jet A1, innehåller olika svårreagerade svavelföreningar. Problemet med bränslena är att de har ett relativt högt svavelinnehåll. Svavelföreningarna riskerar att förgifta katalysatorerna i de nedströms kommande processerna, inklusive bränslecellen själv, och måste därför avsvavlas.

Genom att omvandla komplicerade svavelföreningar till vätesulfid, som i sin tur tillfångatas i en adsorptionspatron, är väteavsvavling ett effektivt industriellt tillvägagångssätt att avsvavla på.

Syftet med detta examensarbete har varit att undersöka möjligheten att, på mikroskala, katalytiskt avsvavla jetbränslet Jet A1, till en svavelhalt acceptabel för bränslecellsinmatning. Detta har inneburit framtagning av en lämplig reaktor och optimering av reaktionsparametrar, tillverkning och utvärdering av katalysatorer samt analys av produkt.

Reaktorsystemet var uppställt i en ugnsliknande omgivning. Reaktorn var omsluten av en värmare i ett isolerat kärl och höll konstant temperatur. Samtliga katalysatorer prövades först vid identiska processbetingelser för att jämföra deras inbördes aktivitet. De två bäst presterande katalysatorerna i denna undersökning var CoMo-CA och PPt-47. CoMo-CA består av kobolt, molybden och nickel, på en support av aluminiumoxid, och citronsyra användes för att optimera spridningen av den aktiva fasen vid tillverkningen av katalysatorn. PPt-47 är en ädelmetallkatalysator bestående av endast platina på en support av aluminiumoxid. Denna tillverkas av Stonemill AB.

Vidare användes dessa katalysatorer i detaljerade tester, som kördes på både tiofen och dibensotiofen (DBT), för att avgöra vilka processbetingelser som fungerade bäst. Sist ut testades katalysatorernas förmåga att avsvavla Jet A1 vid ett skarpt försök.

Det högst uppmätta resultatet på Jet A1 var en omsättning av svavel på 98,2 %, vilket utfördes vid de tuffaste processbetingelserna, med CoMo-CA katalysatorn. Sammanfattningsvis kan det konstateras att CoMo-CA genomgående hade en högre svavelomsättning än PPt-47 samt att en svavelhalt på 13,3 ppm uppnåddes. Denna halt är gångbar i en högtemperaturbränslecell. (Less)
Please use this url to cite or link to this publication:
author
Karstensson, Johan LU and Jönsson, Nicklas LU
supervisor
organization
course
KET920 20161
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Jet fuel, DBT, thiophene, HDS, catalysis, kemiteknik, chemical engineering, Jet A1
language
English
id
8893555
date added to LUP
2016-11-15 13:56:29
date last changed
2016-11-15 13:56:29
@misc{8893555,
  abstract     = {Logistic fuels such as diesel and petrol, in which Jet A1 is included, are sulfur-containing fuels used for transports. The main problem with logistic fuels, when used in fuel cell (FC) applications, is their relatively high concentration of sulfur compounds. The sulfur compounds might poison the catalysts in all of the downstream processes, including the FC itself.

Hydrodesulfurization (HDS) is an industrial approach for effective desulfurization of fuels by converting complicated organic sulfur compounds into hydrocarbons and hydrogen sulfide (H2S), which in turn can be trapped in an adsorption cartridge. This thesis focused on a miniaturization of said technology, i.e. a µHDS-system for logistic fuels, in small-scale fuel cell systems.

The goal was to desulfurize Jet A1 for utilization in FC-applications. Through investigation and evaluation of different catalysts and process parameters, a catalytic reactor system was developed. Desirable was to achieve a sulfur level below 10 ppm which is low enough for injection into a FC.

The approach was to set up a micro-scale plug flow reactor (PFR) in which the effects of temperature (260 °C – 450 °C), pressure (2 bar – 8 bar) and LHSV (1 h-1 – 4 h-1), on catalytic activity, was investigated. Incipient wetness impregnation was used for the preparation of six different catalysts, which were tested in said reactor. Detailed investigations were done on a Pt/alumina (PPt-47, manufactured by Stonemill AB) catalyst as well as on a CoMo/alumina catalyst impregnated with citric acid (CA). Their activity was determined based on the conversion of thiophene and dibenzothiophene (DBT). As a final test, Jet A1 was desulfurized using the same two catalysts.

CoMo-CA was consistently the better performing catalyst compared with PPt-47, reaching a sulfur conversion of 98.2 %, compared to 93.2 % when tested with Jet A1 at the most severe reactor settings. A sulfur level of 13.3 ppm was achieved with the CoMo-CA, applicable in a high-temperature FC.},
  author       = {Karstensson, Johan and Jönsson, Nicklas},
  keyword      = {Jet fuel,DBT,thiophene,HDS,catalysis,kemiteknik,chemical engineering,Jet A1},
  language     = {eng},
  note         = {Student Paper},
  title        = {µHDS system for desulfurization of logistic fuels for fuel cell applications},
  year         = {2016},
}