Effect of support and cobalt precursors on the activity of Co/AlPO4 catalysts in Fischer–Tropsch synthesis

ZSM-5 Supported Cobalt Catalyst for the Direct Production of Gasoline Range Hydrocarbons by Fischer–Tropsch Synthesis

“…Except for Co/ZSM-5 catalyst having a Si/Al ratio of 15, TPR profile of the other three catalysts shows a distinctive shoulder peak around 340°C and an intense second peak (T max ) around 380°C. However, the peaks were noticed at lower temperatures than those observed in Al 2 O 3 supported cobalt-based catalyst [16]. The small peak intensity at high temperature region above 600°C suggests the facile reduction of cobalt oxide with a little formation of inactive cobalt aluminates or silicates.…”

Thermally Stabilized Cobalt‐Based Fischer–Tropsch Catalysts by Phosphorous Modification of Al2O3: Effect of Calcination Temperatures on Catalyst Stability

“…[1][2][3][4][5] In general,c obalt-based FTS catalysts have been known to have the advantageous characteristics of producing heavy hydrocarbons with ah ighera ctivity and al ower water gas shift activity [6] compared to ironbased FTS catalysts. [1,9] In our previous works, [10,11] the cobalt-based FTS catalysts modified with phosphorous species on Al 2 O 3 supports exhibited ah igherF TS activity and ah igher stabilitya ta no ptimal amount of phosphorous modifier.These positive effects on the phosphorous-modified Co/Al 2 O 3 could be explained by the suppressed transformation of cobalt oxidest oi nactive cobalt aluminate species with the inhibited sintering phenomena of active metallic cobalt particles. [7,8] Catalyst deactivation can be induced by the aggregation of active metals, the formation of inactive cobalt aluminates by forming strong metal-support interactions, and coke/heavy-wax depositions inside of the inner pores of the supports.…”

“…%c obalt metal to the supports. [10,11] The presence of bimodal pores with as ize of approximately 5-6 and 10 nm, which were more significant on CoPAl, would be beneficial for increasing cobalt particle dispersion and facile mass-transport of heavy hydrocarbons formed during FTS reaction. Above the calcination temperatures of 400 8C, the surfacea reas of CoAl and CoPAl are steadily decreasedt o1 48 and 169 m 2 g À1 on CoAl(700) and CoPAl(700), respectively.H owever,t he decreases of surface areas at higher calcination temperatures are found to be less significant for CoPAl, whichs uggests the increased thermal stability of cobalt particles on the phosphorous-modified P-Al 2 O 3 support.…”

“…However,t he surfacea reas are increasedf rom 110t o2 44 m 2 g À1 on CoAl and 126 to 233 m 2 g À1 on CoPAl by increasing the calcination temperature from 100 to 400 8C, and the largest surfacea reasa re observed on CoAl(400) and CoPAl(400). [10] Particle sizes of cobalt analyzed by XRD, TEM, and chemisorptionmethods The phosphorous modification of Al 2 O 3 is known to enhancet he thermals tabilityb yl ocally forming aluminum phosphate on the Al 2 O 3 surfaces.…”

Catalytic Performance for Hydrocarbon Production from Syngas on the Promoted Co-Based Hybrid Catalysts; Influence of Pt Contents

“…TPR profiles of three promoted CoAl2O3/ZSM-5 (including Pt of 0.1, 0.3, and 0.5) catalysts also show a distinct peak at below 203-204 o C and an intense second peak at a maximum temperature (Tmax) around 292-298 o C which could be assigned to complete reduction of cobalt oxides to metallic cobalt. The peak intensity at higher temperature region around 700 o C suggests the possible transformation of cobalt oxide to the inactive cobalt silicates on catalysts [16,17]. On the other hand, Co-Al2O3/ZSM-5 and CoAl2O3-Pt(0.05)/ZSM-5 showed one peak only at the low temperature around 422 and 321 o C. TPR peaks of Co-Al2O3-Pt(0.5)/ZSM-5 catalyst appearing at around 204 and 292 o C could be assigned to the easily reducible cobalt crystallites to metallic state at lower temperatures.…”