The desulfurization performance of the UDS solvents was investigated at an industrial side-stream plant and was compared with that of MDEA solvent. A mass transfer performance model was employed for explaining the COS absorption into different solvents. Meanwhile, the regeneration performance of the UDS solvents was evaluated in side-stream tests. Results indicate that under the conditions covering an absorption temperature of 40 °C, a pressure of 8.0 MPa, and a gas to liquid volume ratio (V/L) of around 230, the H2S content in purified gas can be reduced to 4.2 mg/m 3 and 0 by using solvents UDS-II and UDS-III, respectively. Moreover, the total sulfur content in both purified gases is less than 80 mg/m. As a result, the UDS-III solvent shows by 30 percentage points higher in COS removal efficiency than MDEA. In addition, the total volume mass transfer coefficient of UDS solvent is found to be twice higher than that of MDEA. Furthermore, the UDS solvents exhibit satisfactory thermal stability and regeneration performance.
Six Ni-Mo catalysts with different metal contents were prepared and characterized by N2 adsorption and X-ray diffractometry. The active phase microstructure of these catalysts was examined by the Raman spectroscopy, temperatureprogrammed reduction(TPR), X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Hydrodesulfurization(HDS) activity of catalyst samples were analyzed in a flow fixed-bed microreactor. The sulfidation degree of Mo and the length of the MoS2 slab slightly increased with the amount of metal loaded following sulfidation. This small change is attributed to polymolybdate species observed in all the oxidized catalysts. Weak metal-support interactions, as determined by the TPR technique, increased the NiSx sulfidation phase and MoS2 slab stacking. The HDS activity of the catalyst samples increased with the number of active sites. For high metal loading catalysts, their HDS activity was nearly identical because the sulfur atoms cannot easily approach active sites. This change is caused by the large number of stacked layers in the MoS2 slabs as well as the decrease in the specific surface area and pore volume of the catalyst samples with an increasing metal loading.
Thermal upgrading of vacuum residue mixed with waste plastics was studied in a laboratory scale delayed coking unit.The model of feed thermal decomposition was set up and the first order reaction kinetics was used to predict products distribution during the coking process.The distillate yield was higher(70%) for the vacuum residue/polystyrene(VR/PS) feed system and the vacuum residue/low density polyethylene(VR/LDPE) feed system.The resulted distillate yield was separated into fractions according to their boiling points,with gasoline and diesel being our fractions of concern.The activation energy was higher for gasoline production(around 60 kcal/mol) varying with the type of feed system,while it was 33 kcal/mol for diesel fraction.The regression coefficient R was 0.990.
The performance of four formulated solvents （labeled as UDS-I, UDS-II, UDS-III, and UDS-IV） for removingmethyl mercaptan from liquefied petroleum gas was predicted based on a two-dimensional solubility parameter theory. Thecalculation results show that UDS-IV has the closest solubility parameter to that of methyl mercaptan as compared withother tested solvents, indicating the strongest affinity and the highest solubility for methyl mercaptan. The industrial tests ata plant for desulfurization of LPG produced from the delayed coker have shown that the UDS solvents have the excellentperformance for removal of organosulfur compounds （mainly methyl mercaptan）. Although the sulfur loading dramaticallyincreases, the total sulfur content of LPG treated with UDS-IV can be reduced by about 50% in comparison with N-methyldiethanolamine. In addition, UDS-IV has superior regeneration performance and selectivity for sulfur compounds over hydrocarbons.The industrial test and the solubility parameter calculation results are in good agreement with each other.
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