Vol.:(0123456789) 1 3 Chemical Papers https://doi.org/10.1007/s11696-018-0565-9 ORIGINAL PAPER Fischer–Tropsch synthesis: efect of silica on hydrocarbon production over cobalt‑based catalysts Elham Yaghoobpour 1  · Yahya Zamani 1  · Saeed Zarrinpashne 1  · Akbar Zamaniyan 1 Received: 10 April 2018 / Accepted: 30 July 2018 © Institute of Chemistry, Slovak Academy of Sciences 2018 Abstract Support materials have an important role in Fischer–Tropsch synthesis (FTS) catalyst and are infuenced by various factors. In this paper, the efects of silica augmentation to γ-Al 2 O 3 supported cobalt material on morphology and performance of catalyst have been studied. A series of catalysts, contain 0, 5, 10, and 15 wt % SiO 2 , were prepared using the incipient wet- ness impregnation method. The prepared catalysts were characterized by various techniques such as BET, H 2 -TPR, XRD, and HRTEM. Then, the catalysts were tested in a fxed-bed reactor. The results showed that the addition of SiO 2 material remarkably promoted the catalyst performance in terms of CO conversion, catalyst activity, and consequently catalytic yield. Among the synthesized catalysts, the catalyst with 10 wt% silica demonstrated an optimum silica addition to achieve the highest catalyst performance. Keywords Fischer–Tropsch synthesis · Cobalt catalyst · γ-Alumina support · Silica efect Introduction Petroleum industry has to consider substitute resources to meet their production needs because of rapid decline of world petroleum reserves, and increased demands for liquid fuels. Fischer–Tropsch synthesis (FTS) is a highly attrac- tive route for producing ultra-clean fuels from natural gas, coal, and biomass without undesirable components such as sulfur, nitrogen, and aromatic compounds (Sari et al. 2009; den Otter et al. 2016). The catalyst may be regarded as the crucial part of FTS technology. The FTS catalyst is typically composed of active metal, support, and promoter (Bartholomew and Farrauto 2005). Among numerous stud- ied catalytic materials, cobalt (Co) and iron (Fe) catalysts have become two accepted commercial catalysts in the FTS process. The cobalt-based catalysts compared to iron-based catalysts are more preferable due to their high activity, high selectivity toward long chain parafns, and low content of by-products (Davis 2007). It is generally accepted that FTS, over Co catalyst with metal particle size larger than 5–7 nm, would be a structure-insensitive reaction (Iglesia et al. 1992; Enger et al. 2011). Thus, the activity of Co catalyst would depend on the number of exposed Co metal sites on the cata- lyst surface. Based on this fact, supports with high surface area (i.e., SiO 2 , Al 2 O 3 , TiO 2 and carbon materials) were con- ventionally used to increase the number of active Co metal sites, (Khodakov et al. 2007; Savost’yanov et al. 2016; Raz- mara et al. 2017). Among all supports, γ-Al 2 O 3 material has been frequently utilized as a support for Co-based catalyst in FTS process due to the adequate thermal stability, high surface area, and mechanical strength (Shimura et al. 2015; Bahadoran et al. 2017). The process of catalyst reducibility turned into a crucial parameter, since the activity of the cata- lyst directly depends on the number of available active sites. The strong interaction of γ-Al 2 O 3 support with Co oxide suppresses the reduction of Co oxide and thereby suppresses the catalyst activity (Shimura et al. 2015). In this regard, a small amount of noble metals is added to Co/γ-Al 2 O 3 to overcome this shortcoming (Ma et al. 2011; Jacobs et al. 2002a, b; Borg et al. 2009). Presumably, noble metals such as Ruthenium (Ru) enhance the reduction of the Co oxide by hydrogen dissociation and spillover from the surface and in turn increase the number of active Co metal sites (Iglesia et al. 1993; Ma et al. 2012). Furthermore, addition of small amounts of other metal promoters has promotional efect on the activity and selectivity of Co/γ-Al 2 O 3 catalyst. For * Yahya Zamani yahyazamani@yahoo.com 1 Gas Research Division, Research Institute of Petroleum Industry (RIPI), West Blvd. Of Azadi Sport Complex, Tehran 1485733111, Iran