Organic nitrogen compounds in gas oil blends, their hydrotreated products and the importance to hydrotreatment

In the pretreatment of feeds for catalytic cracking and for HDA, the primary objective is to reduce the amount of organic sulfur and nitrogen compounds in the feedstock [Catal. Rev.-Sci. Eng. 36 (1994) 75] [1]. Organic nitrogen compounds have a significantly negative kinetic effect on hydrotreating reactions. The distribution of the organic nitrogen compounds in feed and hydrotreated products is discussed. Alkyl-substituted carbazoles are found to be the dominant and most refractive organic nitrogen compound in the feed. Our results show that indoles and quinolines are very reactive as compared with carbazoles. From the characterization of the pyrrole benzologues, it is concluded that the more the substituents, the lesser the reactivity. It is well known that conversion of organic sulfur occurs via two different mechanistic routes: the direct and the hydrogenation route [J. Catal. 61 (1981) 523; AIChE J. 27 (1981) 663; J. Catal. 97 (1986) 52; Catal. Today, in press; Polyhedron 16 (1997) 3213] [2, 3, 4, 5 and 6]. The hydrogenation route converts the most refractive S-molecules and plays a very important role in the conversion of N-compounds. N-containing molecules often show a very low reactivity as compared with the analogous sulfur compounds. Several studies using model feedstocks show that nitrogen-containing molecules, and in particular, basic organic nitrogen compounds inhibit the HDS reaction [Appl. Catal. A 170 (1998) 1] [7]. In this study, real feed experiments have demonstrated that even though carbazoles are slow to react and are among the predominant N-compounds, it is the basic N-compounds that are the major inhibiting species in diesel fuels.     

Encapsulation of transition metal sulfides in faujasite zeolite for hydroprocessing applications

The dispersion of the sulfides of Co, Ni, Mo and W—and their combinations—in the micropores of acidic faujasite zeolite is a challenging task. While a close proximity of the hydrogenation function to the acidic cracking sites is thought to be beneficial for industrial hydrocracking applications, the genesis of well-defined metal sulfides in a tunable environment allows to address two important fundamental issues: (i) the possible existence of an optimum cluster size of metal sulfides with respect to hydrodesulfurization activity and (ii) an extension of the well-known support effect in hydrotreating catalysis. This review will concentrate on the various preparation methods—ranging from the brute-force chemistry involved in dispersing anion precursors to the occlusion of well-defined organometallic complexes in the zeolite micropore space, characterization to determine the successful genesis of suitable models and activity tests.

Successful dispersion of these sulfides in the micropores of faujasite is only possible by careful preparative methods, either using well-dried cation-exchanged precursors or organometallic complexes. A synergistic effect of acidic protons on the metal sulfides is noted. However, the relatively low activities of ultra-dispersed Mo- or Co-sulfide particles compared to those of particles on more traditional supports force us to conclude that there must be an optimal size for metal sulfide clusters larger than those stabilized in the micropores. Although there are some indications that a sulfided CoMo cluster can be formed in the micropores using organometallic precursors, the synergistic effect between the two metals is quite small. From an application point of view, the detrimental effect of bases such as water or nitrogen compounds to the final dispersion of the metal sulfides is problematic. Nevertheless, model studies indicate that a close proximity of acidic and hydrogenation components decreases coking deactivation.     

加氢处理温度对渣油中杂质脱除率的影响

利用渣油加氢中试装置,考察了原料渣油在不同反应温度下经级配催化剂加氢处理前后渣油性质的变化,揭示了硫、氮、镍、钒和残炭的脱除分布规律。结果表明,在恒定温度下,随催化剂活性增加,加氢处理渣油中硫、氮、镍、钒和残炭的含量降低;随反应温度升高,同一反应器得到的渣油杂质含量降低。硫、氮、镍、钒和残炭的总脱除率随反应温度增加而增加,但杂质在各反应器中的脱除率分布不同,50％的镍和60％的钒在前两个反应器中脱除,硫主要在R3和R4反应器中脱除,氮主要在R4和凡反应器中脱除,而残炭则在R5、R4和R5反应器中脱除,随温度变化杂质的脱除率分布呈现各自的变化趋势。     

Bio gas oils with improved low temperature properties

During hydrodeoxygenation of triglycerides to motor fuel the isomerization reactions have an important role, since the cold flow properties of the product are improved significantly by increase of isoparaffin content of the product in gas oil boiling range. Accordingly, the aim of our research program was to select and investigate suitable catalyst(s) for producing relatively high isoparaffin containing product for a long time of preserved activity. Both not-presulphided CoMo/Al₂O₃ and NiMo/Al₂O₃ catalysts have isomerization activity, however, in the case of CoMo/Al₂O₃ catalyst triglyceride conversion is higher by 25.1-30.5 abs%, as well as yields by 24.2-24.6 abs% corresponding by 0.18-0.33 higher i-/n-paraffin ratio than for NiMo/Al₂O₃ under favorable conditions. Thereby products with more advantageous cold flow properties can be produced on CoMo/Al₂O₃ catalyst.     

Study on high-performance unsupported Ni–Mo–W hydrotreating catalyst

A new unsupported hydrotreating catalyst with binder has been prepared by a reflux method. BET, XRD, TEM characterization results show that the catalysts have high surface area and dense active phase. Pilot plant results also show that the new catalyst exhibits much better hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) performance than the traditional supported catalyst.     

助剂对沸腾床渣油加氢催化剂结构性能的影响

考察了单一助剂和复合助剂组合对沸腾床渣油加氢催化剂结构性能的影响。结果表明助剂的加入显著改善了催化剂的加氢活性及转化率,可以选择不同的助剂组合来制备适用于沸腾床工艺的渣油加氢催化剂。     

渣油加氢处理成套技术的研究

考察了渣油固定床加氢处理工艺用用料的主要性能指标如金属钠,粘度和残炭（CCR）等对催化剂活性的影响,确定了设计原料油中杂质含量指标范围,同时,对“S－RHT”催化剂级配工艺进行了研究,从中选出最佳方案。催化剂稳定性实验结果表明催化剂活性和稳定性良好,为盛大技术开发成功提供了理论依据和实际参考数据。     

Y/composite titania-silica (CTS) supported catalyst for hydrotreating coker gas oil

Y/composite titania-silica (CTS) support was prepared by the in situ growth of CTS on HY zeolite. The effects of HY zeolite pretreatment and Y/CTS modification with P and F for adjusting the acidity of the support were studied. The results showed that the structure of Y/CTS was in the form of CTS as shell and HY zeolite particles as core. The content of HY zeolite affected the acidity, acidity distribution and pore structure of Y/CTS. The density of strong acid sites on the HY zeolite surface could be partly reduced by dealumination with citric acid. This reduced the CTS coverage on the outer surface of the HY zeolite, leading to the increased acidity of Y/CTS. The acidity distribution of the support could also be adjusted by P and F modification. Hydrotreating catalysts were prepared with Y/CTS as support. The catalysts were tested using the hydrotreating reaction of a coker gas oil (CGO). The experimental results showed that the catalyst hydrodenitrogenation (HDN) performance could be remarkably improved by adjusting the acidity of the catalyst support via HY zeolite pretreatment and P and F modification. The catalysts with proper Brönsted (B) acidity and Lewis (L) acidity behaved well in hydrodesulfurization (HDS) and HDN performances.     

Infrared studies of nitric oxide adsorption on reduced and sulfided P-Ni-Mo/Al2O3 catalysts

A series of P-Ni-Mo/Al₂O₃ catalysts with varying phosphorus content, prepared by co-impregnation, was studied by infrared spectroscopy of nitric oxide adsorption on their reduced and sulfided form. It was found that small concentrations of phosphorus (1 to 3 wt.-% P₂O₅) increased reducibility and sulfidability of nickel and molybdenum. A red shift of the band of nitric oxide adsorbed on molybdenum is observed for sulfided samples with low phosphorus content compared to phosphorus free. In the samples with high phosphorus contents (above 4 wt.-% P₂O₅) reducibility and sulfidability of nickel and molybdenum decreases. A blue shift of the band of nitric oxide adsorbed on molybdenum is observed and three types of nickel species are found with different degree of reduction/sulfidation in the sulfided form of these samples.     

制备条件对镍基石油树脂加氢催化剂的影响

采用共沉淀法制备镍基催化剂的前躯物,该前躯物经捏合成型焙烧后制成石油树脂加氢催化剂。对沉淀工艺条件、助剂及不同镍盐进行考察。结果表明,通过调整沉淀工艺条件参数,可以制备出适合石油树脂加氢所需的大孔催化剂;选择合适的镍盐和助剂,能够制备出镍晶粒较小的镍基催化剂,同时助剂的加入抑制了Ni晶粒的增长并提高催化剂容硫能力。制备的镍基石油树脂催化剂具有很强的烯烃饱和性能,且加氢后石油树脂的软化点下降幅度很小。加氢前后的石油树脂结构变化很小,说明所制备的催化剂具有很强的烯烃饱和性能,且加氢后石油树脂的软化点下降幅度很小。