Promoter Effect on the Physico-chemical Properties of Cobalt Based Catalyst for CO Hydrogenation

Sukkathanyawat, Hussanai; Tungkamani, Sabaithip; Phongaksorn, Monrudee; Rattana, Tanakorn; Narataruksa, Phavanee; Yoosuk, Boonyawan

doi:10.1016/j.egypro.2015.11.505

Cited by 12 publications

(4 citation statements)

References 9 publications

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“…In the current literature, there is a large discrepancy between conditions and a manner of hydrogen chemisorption measurements, from which data are used to determine the average size of crystallites and dispersion of the metallic cobalt phase deposited on an oxide support. Although those, already old, recommendations, only in the 2015-beginning of 2016 period the much lower temperature, 293-323 K, of hydrogen chemisorption [28][29][30][31][32][33][34][35][36][37] and flow adsorption pulse and TPD methods [32][33][34][35][36][37] are used in many laboratories. The higher, 423 K, temperature of hydrogen chemisorption was also applied in the pulse method for estimation of the average size of cobalt crystallites [33].…”

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confidence: 99%

Estimation of Average Crystallites Size of Active Phase in Ceria-Supported Cobalt-Based Catalysts by Hydrogen Chemisorption vs TEM and XRD Methods

et al. 2016

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Cobalt catalysts with CeO 2 support, unpromoted and promoted with potassium were prepared by an impregnation method. Reduced catalysts were subjected to hydrogen chemisorption at different temperatures in the range of 313-453 K. Studies have shown that calculated Co crystallites size depends on the temperature of chemisorption. The average of size crystallites of the Co active phase obtained from the total and strong chemisorption data were compared with those from measurements by other techniques, TEM and XRD. The results of comparison allowed us to indicate the most suitable chemisorption temperature, different for unpromoted (383 K) and potassium-promoted (413 K) catalysts to determine the proper Co crystallites size of active phase, compatible with the crystallites size determined by the most objective method, i.e. by TEM measurements. In the case of small metal crystallites of active phase (4-5 nm) the divergence of their average size determined by hydrogen chemisorption and TEM methods and particularly by the XRD method is definitely higher than that in the case of larger crystallites (~12 nm).can significantly influence on obtained results. More than 40 years ago Bartholomew et al. [23][24][25] show that the chemisorption of hydrogen over cobalt catalysts with various supports (SiO 2 , Al 2 O 3 , C, MgO, ZSM-5, TiO 2 ) and over unsupported cobalt is activated and highly reversible. The activation was a function of the interaction of cobalt with a support or promoter. Frequently used in catalysis, potassium promoter significantly increased the adsorption activation energy for hydrogen [26]. It is also proved that some methods for determining the hydrogen uptake, i.e. flow adsorption methods such as thermal desorption and pulse methods, measure only irreversible (strong) chemisorption [23,27]. No hydrogen desorption was detected for MgOand ZSM-5-supported and low-loaded (1-3 wt.%) aluminasupported cobalt catalysts using TPD method, even though those catalysts adsorbed hydrogen when the static technique was applied [23,24]. The special case is the Co/TiO 2 system, where due to the strong metal-support interactions the stoichiometry of hydrogen chemisorption is lower than one hydrogen atom per surface cobalt atom, even in static measurements. With exception of the cobalt systems in which the strong metal-support interactions take place, the static technique was recommended for estimation of the average size of cobalt crystallites on the basis of maximal hydrogen chemisorption uptake, usually at 373 K. A good correlation with TEM measurements was found for the Co/SiO 2 , Co/γ-Al 2 O 3 and Co/C catalysts. The paper [9] also shows that the volume of chemisorbed hydrogen (including strong and weak chemisorption) on the CoRe/γ-Al 2 O 3 catalyst varies with the temperature of chemisorption, and the use of different data leads to the determination of different average size of crystallites, even though the actual crystallites size remains unchanged. They obtained the best results when the total chemisorption...

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Estimation of Average Crystallites Size of Active Phase in Ceria-Supported Cobalt-Based Catalysts by Hydrogen Chemisorption vs TEM and XRD Methods

et al. 2016

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“…It is because of this concept that promoters gained attention and led researchers to find convectional ways to establish promoter effects on FT catalysts. Promoters are deposited in small amounts on catalysts to enhance catalyst performance and stability [14,[108][109][110][111][112]. In numerous circumstances, the effects of promoters are interconnected creating a tough decision to exactly tell the real role brought by such a promoter.…”

Section: Support Promotionmentioning

confidence: 99%

Advances on Catalyst Support Modification and their Effect on Fischer Tropsch Synthesis: A Review

Thibanyane,

Gorimbo,

Yao

2024

Preprint

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One important goal of research on heterogeneous catalysis for Fischer Tropsch synthesis (FTS) is to understand the connection linking catalyst morphology and its activity. Development of these effective catalysts highlights the potential for understanding the effectiveness of promoted supported catalysts and revealing their complex and dynamic effects in FTS. The metal-support interaction (MSI) is influenced by the physicochemical and textural features provided by the modified support and can directly influence the sizes of active metal crystallites, reactants and/or products mass transfer, dispersion, mechanical strength, stability and consequently the adsorption-desorption characteristics of the catalyst. Herein, this article explores the general strategies for modifying silica supports (achieved through doping, coating, or promoting the support or support precursor) and how these strategies can be manipulated to further alter catalyst performance and product selectivity by enhancing the amount of active metal species and improving the intrinsic turnover frequency (TOF). Furthermore, the review emphasises a new strategy (the inverse model of the silica support modification) aiming at overcoming the challenges posed by active metal coating or coverage, as well as pore blockages by promoters that occur during conventional preparation of promoted silica supported FT catalysts.

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“…Evaluating different kinds of catalyst supports and active sites are highly required to further enhance the process performance and LPG production, inserting promoters to the bifunctional catalyst is one of the good options [116,117] . The effect of Ca addition as a promoter had been evaluated by Ma et al.…”

Section: State Of Art Updates On the Conversion Of Syngas To Lpgmentioning

confidence: 99%

A Review on the Conversion of Synthetic Gas to LPG over Hybrid Nanostructure Zeolites Catalysts

Al-Qadri

Nasser

Galadima³

et al. 2022

ChemistrySelect

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Recently, Liquified petroleum gas (LPG) attracts wide applications due to its high heating value and clean combustibility. An innovative approach to synthesis of LPG from syngas was established based on Fisher-Tropsch (F-T) technology. However, the conversion and selectivity are generally low with the classical catalysts. The hybrid system of methanol and zeolitebased catalyst was established as a potential approach to promote such a process. To strongly overcome the large demand of LPG and grasp the research work in this subject, a comprehensive review became necessary. LPG is basically produced from syngas through the direct method, where most recent studies lay on, and the indirect or semi direct approach. There were several factors affecting the process performance, which mainly are the reaction temperature, reaction pressure, type of the hybrid catalyst, carbon monoxide to hydrogen ratio, mixture flow rate, and time-on-stream of the reaction. The most common reaction conditions reported in the literature are 260-400 °C, 10-50 bars and H 2 to CO ratio of 2. However, the most important parameter considered was the catalyst, which is a key factor of interest. The two main issues controlling the catalyst performance were the synergetic effect between the two hybridized catalysts and the used type of zeolite. It was perceived that the higher the zeolite membered rings the better the LPG selectivity (i. e., BEA, and USY provided the higher LPG production rate).

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Promoter Effect on the Physico-chemical Properties of Cobalt Based Catalyst for CO Hydrogenation

Cited by 12 publications

References 9 publications

Estimation of Average Crystallites Size of Active Phase in Ceria-Supported Cobalt-Based Catalysts by Hydrogen Chemisorption vs TEM and XRD Methods

Estimation of Average Crystallites Size of Active Phase in Ceria-Supported Cobalt-Based Catalysts by Hydrogen Chemisorption vs TEM and XRD Methods

Advances on Catalyst Support Modification and their Effect on Fischer Tropsch Synthesis: A Review

A Review on the Conversion of Synthetic Gas to LPG over Hybrid Nanostructure Zeolites Catalysts

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