Hydroprocessing of low-temperature coal tar (LTCT) for the production of clean fuel was investigated over fluorinated NiW/Al2O3–SiO2 catalyst in a fixed bed reactor. A series of NiW/Al2O3–SiO2 catalysts with different F-loading were prepared by incipient wetness coimpregnation and characterized by various techniques such as nitrogen adsorption, FT-IR, XRD, SEM TPD-NH3, and XPS. The effects on the yield, properties of liquid products, and gas components from using fluorinated NiW/Al2O3–SiO2 catalysts were discussed. In addition, coke formation was also evaluated by TG-DTG. The result showed that the introduction of F influenced both acidity and active phase while have little effect on crystalline structure of NiW/Al2O3–SiO2 catalysts. Lower F-loading in the NiW/Al2O3–SiO2 catalysts not only improved catalytic performance but also was helpful to improve some of the physicochemical properties of liquid product including dynamic viscosity, density, distillation range and hydrocarbon content, and so on. The optimal F concentration to NiW/Al2O3–SiO2 is 1.0 wt %, at which the highest naphtha and diesel yield was obtained due to its appropriate acid distribution and more active phase. Meanwhile, liquid product produced displayed the lowest N content (78.6 ug/g) and density (0.8507 g/mL). Furthermore, compared with feedstock, phenols almost disappeared and phenyl cycloalkanes (PCA) and cycloalkanes (CA) are rich in hydrogenated product.

The experiment of fuel oil production through hydrogenation has been conducted on a hydrorefining− hydrocracking two-stage serial fixed-bed reactor with coal tar distillate [CTD; initial boiling point (IBP)−360 °C] and phenol extraction coal tar distillate (PE-CTD) as the feedstocks. By comparison of the changes in chemical composition and carbon number distribution as well as product distribution and properties before and after hydrogenation in the two feedstocks, the influences of phenol extraction treatment on fuel oil production with coal tar hydrogenation were studied. The experimental conditions of this study include the reaction pressure of 13 MPa, liquid hourly space velocity of 0.5 h −1 , hydrorefining reaction temperature at 360 °C, hydrocracking reaction temperature at 380 °C, and filling proportion of hydrorefining catalyst/ hydrocracking catalyst of 1:1. The experimental result shows that phenol extraction reduces the naphtha yield by 8.69 wt % but produces 13.58% of mixed phenols. Furthermore, the phenol extraction treatment is favorable for converting a heavy distillate of coal tar to a light fraction.

No abstract

China is one of the largest coal producers in the world and abundant coal tar is produced from coal gasification and carbonization every year. Thus, catalytic hydrotreating coal tar for the production of clean fuel has received substantial attention. In this work, clean liquid fuel was obtained from the catalytic hydrogenation of a low temperature coal tar (LTCT) distillate in a four-stage fixed bed reactor with various catalyst combinations on the pilot scale. Effects of dominant hydrotreating parameters, reaction temperature (290−390 °C), H 2 pressure (8−15 MPa), and liquid hourly space velocity (0.2−0.6 h −1 ), on hydrotreating activity, the intermediate and final products, and chemical components of the hydrogenated oils were evaluated. Meanwhile, a possible reaction scheme for the conversion of alkyl-naphthalenes (AN) and phenols in feedstock was probed. The results showed that the four-stage reacting system was capable of removing sulfur and nitrogen to less than 10 μg/g. Furthermore, after hydrotreating, AN were transformed into decalins, tetralin, and indenes, and alkyl-cycloalkanes (CA) were the main and final products of phenolic compound hydrodeoxygenation (HDO). In addition, coke formation of the spent catalysts was also studied by thermogravimetric techniques, which suggested that the coke deposits are mainly concentrated in the second and third stages of the reactor. The results of this work show that high-quality clean fuels can be obtained through the multistage hydrotreating process with a catalyst gradation technology, which may bridge the gap between fundamental research and industrial production and offer a route for deep processing of LTCT.

No abstract