e-journal

Hydrocarbon production via Fischer–Tropsch synthesis from H2-poor syngas over different Fe-Co/y-Al2O3 bimetallic catalysts

---

Abstract.
Fischer–Tropsch synthesis (FTS) at 20 bar and 483 K, with H2-poor syngas (H2/CO ratio = 1.0) in order to
simulate gasified biomass, was performed over Al2O3-supported catalysts with various ratios of Fe:Co
(12 wt% bimetal) prepared by co-impregnation. Co was found to be incorporated into the Fe2O3 phase
after calcination, at least for the iron-rich samples, while no evidence of Fe incorporated into Co3O4 was
found. Upon reduction, most probably FeCo alloys were formed in the iron-rich bimetallic samples. The
degree of reduction of the catalysts showed a non-linear behavior with respect to the Fe:Co ratio, but it is
obvious that Co increases the reducibility of Fe. Alloying Co with small/moderate amounts of Fe
improved the FT activity compared to the 100% Co catalyst at low conversion levels. Alloying Fe with
small/moderate amounts of Co lowered the FT activity, but increased the relative water–gas-shift (WGS)
activity compared to the 100% Fe catalyst. However, the overall WGS activity was very low for all
catalysts, even with external water addition to the feed, resulting in low FT productivities (per gram
catalyst) due to the low partial pressure of H2. A higher Fe:Co ratio in the bimetallic catalyst generally
resulted in higher relative WGS activity, but did not lower the H2/CO usage ratio to the desired value of
1.0. For the Fe-containing catalysts, the space–time yield of hydrocarbons (HCs) decreased with
increasing partial pressure of water or reduced space velocity, indicating an inhibition of water on the FT
activity, most often resulting in low FT productivity under the conditions with highest relative WGS
activity (usage ratios closest to the inlet H2/CO ratio). Moreover, the co-impregnation technique resulted
in a surface enrichment of Fe, at least for the Co-rich samples, covering the Co sites. For the bimetallic
catalysts, both FT and WGS activities rapidly declined at high partial pressure of water due to
deactivation by oxidation and sintering. However, the results indicate that WGS and FT proceeded over
sites of different nature in the bimetallic catalysts.
The bimetallic catalysts showed essentially no synergy effects with respect to HC selectivities and
olefin/paraffin ratios, which partly can be explained by the use of a sub-stoichiometric H2/CO ratio as
feed. The higher the Fe content, the lower were the C5+ selectivity and C3 olefin/paraffin ratio. Water
addition increased the C5+ selectivity and C3 olefin/paraffin ratio and reduced the CH4 selectivity.

Keywords: Fischer–Tropsch synthesis, H2-poor synthesis gas, Low H2/CO ratio, Water–gas-shift, Cobalt, Iron
Bimetallic catalysts, Alloy

---

Ketersediaan

Tidak ada salinan data

Informasi Detail

Judul Seri

Applied Catalysis B: Environmental

No. Panggil

-

Penerbit

London : Elsevier B.V.., 2009

Deskripsi Fisik

Applied Catalysis B: Environmental 89 (2009) 167–182

Bahasa

English

ISBN/ISSN

-

Klasifikasi

-

Tipe Isi

-

Tipe Media

-

Tipe Pembawa

-

Edisi

-

Subjek

KIMIA

Info Detail Spesifik

-

Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

Komentar

---

Anda harus masuk sebelum memberikan komentar