Jamal A. Anabtawi

Impact of gasoline and diesel specifications on the refining industry

Future gasoline specifications demand reduction in aromatics, benzene, sulfur, volatility, and boiling point. In response, refiners must modify their processing conditions, catalysts, and mode of operation of catalytic reformers and isomerization units. Diesel fuel is also facing tighter specifications for cetane number, aromatic content, sulfur, and color. To meet these specifications, operational modifications include use of higher activity catalysts, higher hydrotreating seventy, and two-stage processing. This paper reviews fuel legislation adopted recently worldwide, and refining technology solutions practiced and / or planned to meet the new specifications.

Prediction of reformate research octane number by FT-i.r. spectroscopy

Abstract Fourier transform infrared (FT-i.r.) spectroscopy was used to calculate the research octane number (RON) of naphtha feed and reformate during the course of performance evaluation of reforming catalysts. Five absorption regions that correspond to aliphatic and aromatic bands within the mid-infrared region were utilized for developing the correlation for RON estimation. Statistical methods were used to derive third degree polynomial equations which could give a better estimate of engine RON. The technique was found to give excellent correlation (R2 = 0.95) with the engine RON data.

Performance evaluation of HDS catalysts by distribution of sulfur compounds in naphtha

Abstract This paper presents results of pilot plant evaluation of two commercial hydrodesulfurization (HDS) catalysts and demonstrates the use of trace sulfur analysis and distribution of sulfur compounds for reliable and better catalyst evaluation. Straight-run naphtha (SRN) and a blend of SRN and hydrocracked naphtha containing 897 and 534 ppm sulfur respectively were analysed for sulfur compound distribution by gas chromatography with flame photometric detection and hydrocarbon type composition by a PONA analyser. G.c.-f.p.d. analysis indicated the presence of 52 sulfur compounds, including mercaptans (55.7%), thiophenes and sulfides (43.1%), disulfides (1.1%) and traces of polysulfides, hydrogen sulfide and elemental sulfur. Pilot plant experiments were carried out with two catalysts at 220–350°C, space velocities of 10 and 13 h−1 and gas rates of 67 and 8011−1. Total and mercaptan sulfur in the product passed through a minimum with increasing temperature. The optimum temperature was 320°C for SRN and 300°C for the blend naphtha. Thiophenes, forming a major portion of the sulfur in the product, could be removed by hydrotreating at >280°C. At higher temperatures, methyl mercaptan increased, owing to hydrogen sulfide recombination reactions. One of the catalysts performed better than the other.

ADVANCES IN THE CHEMISTRY OF CATALYTIC REFORMING OF NAPHTHA

Catalytic reforming of naphtha remains the key process for production of high octane gasoline and aromatics (BTX) which are used as petrochemicals feedstocks. The increased demand for these products has led refiners to investigate ways for improving the performance of the reforming process and its catalysts. Moreover, in order to comply with environmental restrictions, the reduction in lead content would require further increase in the reformate octane number. In response to these requirements, refiners and catalyst manufacturers are examining the role of the catalysts in improving the selectivity to aromatics and in octane enhancement. By understanding the chemistry and the mechanism of the reforming process, higher performance catalysts with longer life on stream and lower cost can be developed. This review covers recent developments in reforming catalysts, process reaction chemistry and mechanism. It also highlights prospective areas of research.

Factors influencing the performance of naphtha hydro-desulfurization catalysts

Abstract The performance of the two CoMo catalysts was evaluated for hydrodesulfurization of two Saudi naphthas in a bench-scale unit under Industrial conditions. Various types of sulfur compounds in the naphtha feed stocks and products were determined by chemical analysis and gas chromatography. The results show that the product sulfur decreased with increasing temperature down to a minimum, followed by an increase at higher temperatures. This increase was attributed to the occurrence of H2S-alkene recombination reaction leading to the formation of mercaptans. The effect of increasing the space velocity was to slightly increase product sulfur, while the hydrogen gas rate had an insignificant effect. The product sulfur for the two catalysts was below 1 ppm in the temperature range 280–350°C. However, one catalyst was selected based on its superior HDS performance attributed to higher concentrations of molybdenum, cobalt and phosphorus oxides.

AN ALTERNATE METHOD TO ESTIMATE REFORMATE OCTANE NUMBER

ABSTRACT This paper presents an alternate method for estimating RON using the reformate density, as an indirect measure of its composition. Reformate samples were obtained from catalytic reforming of naphtha in a pilot plant using different catalysts at various temperatures. Actual RON by engine test of these reformates and their densities were determined. A power law type of equation gave the best correlation (correlation coefficient = 0.94, standard deviation of residuals = 0.45) with the octane numbers determined by ASTM engine tests. The benefits and limitations of the method, in comparison to other methods, are also discussed. It was concluded that, while the method based on density gives comparable accuracy, it is simple, rapid and economical.

Potentials for Diesel Fuel Production by Hydroprocessing of Middle Distillates

Abstract The growing demand for diesel fuel relative to fuel oil has caused refiners to increase conversion of fluid catalytic cracking (FCC) operation. This has increased production of diesel blending components, such as cracked middle distillates, which have poorer storage stability, cetane index, and fuel quality. On the other hand, diesel specifications are expected to decrease the sulfur and aromatic levels to 0.05 wt. % and 10-20 liquid volume%, respectively. Economic evaluation of alternatives to meet diesel specifications showed hydrotreating to be the most feasible. Recent studies have shown that available hydrotreating technologies need further development in catalysts and processes to meet this challenge. This paper reviews the scientific and technical literature regarding the hydrotreating of middle distillate in terms of economics, chemistry, processes, and catalysts, and proposes a new direction in technology development.