| 1. |
- Keller, Martin, 1985, et al.
(författare)
-
Chemical looping tar reforming using La/Sr/Fe-containing mixed oxides supported on ZrO2
- 2016
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 183, s. 298-307
-
Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification gas contains condensable hydrocarbons usually referred to as "tars". The use of chemical-looping reforming (CLR) has been proposed as a downstream technology for tar removal from the hot raw gasification gas. In this work two different ZrO2 support materials impregnated with La, Sr, Fe and mixtures thereof have been investigated as bed material for this proposed CLR process, with benzene and ethylene as tar surrogates. It was found that only combinations of La and Fe yielded significant catalytic activity for benzene conversion that could be further improved by adding Sr. Over this material, the benzene conversion reaction was found to be of first order with respect to benzene, and a simple kinetic model indicates that a high degree of benzene conversion can be obtained at reasonable residence times when the reactor temperature is sufficiently high (T= 850 degrees C). It was also observed that this material exhibited some activity for selective catalytic oxidation of benzene, which could further increase the tar conversion when either the bed material provided oxygen to the gas or a small stream of molecular O-2 was added to the gasification gas feed. XRD analysis of the used bed materials revealed that a pyrochlore phase and SrZrO3 perovskite were formed during the experiment.
|
|
| 2. |
- Keller, Martin, 1985, et al.
(författare)
-
Cu-impregnated alumina/silica bed materials for Chemical Looping Reforming of biomass gasification gas
- 2016
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 180, s. 448-456
-
Tidskriftsartikel (refereegranskat)abstract
- Raw gas derived from low-temperature biomass gasification usually contains condensable hydrocarbons referred to as "tars" as well as other hydrocarbons such as ethylene and other olefins. Reforming of these compounds via Chemical Looping Reforming has been recently proposed. In this work Cu supported on four different Al2O3/SiO2-based porous support materials were investigated for reforming of ethylene. The investigated particles were manufactured by incipient wetness impregnation of the porous support with a copper nitrate solution followed by calcination, and then tested in a small-scale fluidized bed reactor at temperatures between 600 degrees C and 850 degrees C. The ethylene conversion was found to be strongly inhibited by the presence of aromatics in the gas. However, it was found that Cu supported on commercial PURALOX transition alumina catalyst exhibited superior properties, with high degrees of ethylene conversion achievable even in the presence of aromatic compounds. Under the experimental conditions in this work, up to 90% ethylene conversion was obtained at T = 850 degrees C in the presence of high concentrations of benzene. For the other prepared materials, the ethylene conversion was drastically reduced when monoaromatic compounds were present in the feed.
|
|
| 3. |
- Keller, Martin, 1985, et al.
(författare)
-
Use of CuO/MgAl2O4 and La0.8Sr0.2FeO3/gamma-Al2O3 in Chemical Looping Reforming System for Tar Removal from Gasification
- 2016
-
Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 62:1, s. 38-45
-
Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification gas contains condensable hydrocarbons usually referred to as "tars." The use of chemical-looping reforming (CLR) has been proposed as a downstream technology for tar removal. The tar removal capabilities and the regeneration properties of two particularly promising bed materials, CuO/MgAl2O4 and La0.8Sr0.2FeO3/gamma-Al2O3, were investigated using C2H4, C6H6, and C7H8 as tar surrogates. The material La0.8Sr0.2FeO3/gamma-Al2O3 exhibited high levels of conversion of all tar surrogates investigated, whereas CuO/MgAl2O4 showed less promising behavior. For this material, the C2H4 conversion in the absence of aromatic compounds was very high, but in the presence of monoaromatic compounds, the conversion of aromatics and C2H4 was poor. This indicates that monoaromatic compounds hinder the conversion of C2H4 effectively. Therefore, C2H4 may not always be a good choice as a tar surrogate and its suitability may depend on the mechanism of hydrocarbon conversion on the bed material surface in question.
|
|
