PTQ Q4 2024 Issue

Catalyst

CoMo

NiMo

NiW

150 170

190

210

230

150 170

190

210

230

150 170

190

210

230

Temperature [T] (˚C)

Mean (SZ54 yield (wt%)) (Nominal H p ressure (barg)=120) Mean (HS yield (wt%)) (Nominal H p ressure (barg)=120) Mean (C mercaptans yield (wt%)) (Nominal H 2 p ressure (barg)=120)

Mean (SZ54 yield (wt%)) (Nominal H p ressure (barg)=60) Mean (HS yield (wt%)) (Nominal H p ressure (barg)=60) Mean (C mercaptans yield (wt%)) (Nominal H 2 p ressure (barg)=60)

Figure 8 TBPS product yields, H2S, and C4 mercaptans obtained at 60 bar and 120 bar hydrogen pressure, Run02 (blue colour) and Run03 (red colour)

contact times for the reaction to progress from C₄ mercaptan to H₂S. Consistent with the results observed in Run01, the influence of LHSV adhered to expectations. At a given tem - perature, the fraction of unconverted TBPS was greater at higher LHSV (shorter contact times), while trends in product evolution shifted to higher temperatures in reactors operat - ing at LHSV = 1.0 compared to those at LHSV = 0.5. Moreover, the type of catalyst employed exhibited a dis - cernible impact on the decomposition of TBPS. The data presented in Figure 8 revealed that the CoMo catalyst facilitated a faster decomposition of TBPS compared to the NiMo and NiW catalysts. Notably, significant differences were observed in the decomposition of C₄ mercaptans and H₂S, suggesting that the catalyst type played a crucial role in the C-S bond cleavage step, leading to the formation of isobutene and H₂S species. Figure 9 displays the evolution of isobutene and isobu - tane species during the TBPS decomposition. Like Figure 8, the results are presented in quadrants based on the LHSV and gas-to-oil ratio used in the tests. It is important to note that species such as C1 -C 3 and n-butane were excluded from the plot due to their yields falling below 0.5 wt%. At the lowest space velocity, it was observed that isobutane

reached its maximum yield at temperatures above ~220ºC, while the yield of isobutene remained almost negligible under these conditions. In contrast, at LHSV = 1 and gas- to-oil ratio = 500 (fourth quadrant), even at higher temper - atures, isobutene was not entirely converted, resulting in the isobutane yield not reaching its maximum. This discrep - ancy can be attributed to gas contact time, as explained earlier in relation to the evolution of C4 mercaptans. Notably, the CoMo catalyst exhibited a faster isobutene hydrogenation rate compared to the other catalysts, while the NiW catalyst displayed the lowest hydrogenation activ - ity. Nonetheless, due to the lack of physicochemical charac - teristics of the catalysts, a more comprehensive analysis of the results was not possible. In summary, in Run02 and Run03, the decomposition of TBPS over CoMo, NiMo, and NiW catalysts showcased distinct product distributions. The presence of catalysts facilitated the decomposition, with temperature playing a significant role. The LHSV and gas-to-oil ratio had mild effects on the product distribution, primarily impacting the yield of C4 mercaptans. Furthermore, the type of catalyst employed influenced the decomposition process, with the CoMo catalyst demonstrating a faster decomposition rate.

PTQ Q4 2024