two MPa 60 60 s, the the two and 6 Co catalysts shared a comparable trend
2 MPa 60 60 s, the the 2 and six Co catalysts shared a equivalent trend, in that a that increase occurred for all hydrocarbon yields. yields. sharp enhance occurred for all hydrocarbon In contrast for the other systems, where 60 s led to larger yields than ten s all through the pressure range, the six wt Co AZD4625 Ras catalyst displayed a reverse trend at 0.5, 1, 3 and four MPa. At these pressures, the C1 to C3 hydrocarbon yields at 60 s were drastically reduce than that at ten s, implying that within the added 50 s, secondary reactions, namely cracking or hydrogenolysis could have occurred, as a result decreasing the methane, ethane, ethylene and propane concentrations. Aside from secondary reactions, which seem additional influential for the 10 s study (discussed in detail later within this section), higher water yields (higher CO conversion) at the longer residence time of 60 s (and at 3 and four MPa) could have lowered methane production. The rationale behind this trend in conventional FTS is that water is competitive with methane for hydrogen, particularly with rising CO conversion (longer residence time) [304]. For the ten s study, where the arc was stable as much as 10 MPa, the methane, propane and propylene yields normally improved with growing stress, especially involving eight and ten MPa. Even so, the ethane concentration decreased from 57 ppm at 1 MPa to 26 ppm at four MPa, and enhanced to 57 ppm at 10 MPa. Similarly, the ethylene concentration sharply decreased from 39 ppm at 1 MPa to six ppm at four MPa, and decreased slightly up to ten MPa. This six wt Co catalyst’s ethylene trend differed in the other systems at 10 s, exactly where the ethylene yield typically elevated at larger pressures. The decreasing trend with the ethylene (olefin) yields at 10 s, plus the C1 to C3 hydrocarbon yields at 0.five, 1, 3 and 4 MPa, at 60 s, may perhaps all be explained by the literature.Catalysts 2021, 11,eight ofIn traditional FTS, working with cobalt catalysts, the primary olefin yields decreased as a result of readsorption onto the catalyst surface. The readsorbed olefins, based on the operating conditions (temperature, stress and residence time), were then topic to secondary reactions: hydrogenation to paraffins, reinsertion into increasing chains, hydrogenolysis, cracking and isomerization [28,35]. Hydrogenation to paraffins (causing chain termination) was shown to be Goralatide Purity & Documentation dominant at 0.1 MPa (atmospheric stress), whereas reinsertion into increasing chains was dominant at 1 and two MPa (a typical FTS operating pressure) [369]. In this study, there may have been the secondary reinsertion of ethylene into C3 hydrocarbon chains, particularly for the ten s study, which could possibly be indicated by the reduce in ethylene yields and raise in propane and propylene yields with rising pressure. This could have led towards the maximum ethylene yields becoming obtained at lower pressures of 1 MPa at ten s, and 2 MPa at 60 s. In addition, high methane yields in between eight and ten MPa, could have arisen in the hydrogenolysis of readsorbed ethylene (as well as other olefins) dominant secondary reaction above 550 K (277 C) in conventional FTS, which leads to a significant improve in methane selectivity with rising CO conversion (longer residence time) [40,41]. This reaction temperature was attainable at involving eight and ten MPa due to higher plasma heating. On the contrary, the reaction temperature could have been considerably lowered by the active plasma species (pre-dissociated H2 and CO reactants) [425]. Amongst the olefins, ethylene, in particula.