Applied Petrochemical Research (v.4, #4)

The effects of magnesium of Zn–Mg–Al additives on catalytic cracking of VGO and in situ reduction of sulfur in gasoline by Rui Feng; Hamid Al-Megren; Xuejin Li; Mohammed C. Al-Kinany; Ke Qiao; Xinmei Liu; Zifeng Yan (329-336).
The scope of the present study is to describe the cracking behavior of hydrocarbons and the reduction of sulfur in gasoline in fluid catalytic cracking (FCC) process using Zn–Mg–Al additives with varying the Mg/Al molar ratios. Experiments have been carried out on a micro-activity-test (MAT) reactor using high-sulfur vacuum gas oil (VGO) feed and zinc impregnated Mg–Al spinels as additive and the commercial cracking catalyst. It was found that Zn–Mg–Al additives exhibited enhanced Lewis acidity compared with the corresponding Zn-free Mg–Al spinels. The MAT results indicated that the addition of additives reduced the yields of liquid petroleum gas and coke at low Mg contents but increased the coke yield at high Mg contents. Overall, the additives improved the yields of gasoline and diesel. It has also been shown that the rich Lewis acidity had a positive effect on the conversion of aromatic sulfur species of gasoline and the maximum reduction of gasoline sulfur was achieved with Zn/Mg4.0Al2O3 due to the synergistic effect of basicity and Lewis acidity.
Keywords: Fluid catalytic cracking; Gasoline sulfur reduction; Acidity; Magnesium; Coke yield

Study on the catalysts of sulfur-odor gas pollution treatment by Fang Liu; Jinjin Lu; Chaocheng Zhao (337-342).
Aiming at the characteristics and current status of refineries’ odor pollution, the sulfur containing odor gas–hydrogen sulfide was chosen as a typical object and treated by using the adsorption-catalytic oxidation method in the laboratory. This research focused on the preparation of adsorptive catalyst with high sulfur capacity at room temperature. The results showed that the sulfur capacity of walnut shell activated carbon (WSAC) was up to 351 mg/g, specific surface area was 2,030 m2/g, and the pore volume of microspores was 0.608 mL/g. By comparison with the commercial activated carbon, it is found that the specific surface area, the sulfur capacity, and iodine value of WSAC have been improved significantly. The sulfur capacity of WSAC modified by KIO3 with mass fraction of 1 % was up to 459 mg/g.
Keywords: Hydrogen sulfide; Walnut shell activated carbon; Modification; Desulfurization

Combined modification of ultra-stable Y zeolites via citric acid and phosphoric acid by Xuejin Li; Ke Qiao; Lifeng He; Xinmei Liu; Zifeng Yan; Wei Xing; Lihong Qin; Baoqin Dai; Zhihua Zhang (343-349).
The modification of commercial ultra-stable Y zeolites using citric acid and phosphoric acid was investigated systematically via a L18(38) orthogonal experiment. The pore structure, acid property and crystal structural of modified USY zeolites were characterized by a variety of means such as N2 adsorption–desorption, Fourier transform infrared spectroscopy, NH3-temperature programmed desorption and X-ray diffraction. The optimal modification condition is found to be that the volume ratio of citric acid (0.3 mol/L) and phosphoric acid (0.3 mol/L) is 1.0, and the operation is performed at 100 °C for 6 h. The as-synthesized sample presents an increased secondary pore volume up to 0.207 cm3/g which accounts for 42.9 % of the total pore volume, and appropriate acidity distribution as well as good crystallinity. In addition, the USY obtained by 1.0 L scale-up modification possesses a secondary pore volume of 0.210 cm3/g which accounts for 42.4 % of the total pore volume, showing no obvious scale-up effects. Furthermore, the hydrothermal stability of the modified samples meets the requirements of commercial catalysts for hydrocracking. Performance evaluation was carried out on a 200 mL fixed-bed single stage hydrogenation unit using Daqing VGO as feedstock. The 140–370 °C middle distillate yield is 66.09 %, and middle distillate selectivity can reach up to 80.45 %. Compared with commercial catalyst, the yield and selectivity are increased by 5.67 and 4.07 %, respectively.
Keywords: USY zeolite; Modification; Citric acid; Phosphoric acid

Synthesis of hierarchical SAPO-11 for hydroisomerization reaction in refinery processes by Zhipeng Ma; Zhen Liu; Hao Song; Peng Bai; Wei Xing; Zifeng Yan; Lianhong Zhao; Zhongdong Zhang; Xionghou Gao (351-358).
A series of SAPO-11 molecular sieves with hierarchical structure (Meso-SAPO-11) were synthesized by adding certain amount of carbon particles. The co-existing micropore and mesopore feature of Meso-SAPO-11 was confirmed by N2 adsorption–desorption isotherm, TEM and SEM. XRD, TEM, SEM and Py-FTIR were employed to examine the crystallization, morphology and acidity properties of the resulting meso-SAPO-11 prepared from two typical kinds of carbon material and different contents of template. The hydroisomerization performance of meso-SAPO-11 as catalyst support and acid active site, with loading 0.5 wt% Pt as metal active site, was also tested to evaluate the mesoporous effects on catalytic activity and product selectivity.
Keywords: SAPO-11; Hierarchical structure; Hard template; Carbon material; Hydroisomerization

Interaction between Ni and HZSM-5 in aromatization-enhanced reactive adsorption desulfurization catalysts for FCC gasoline upgrading by Jinchong Zhao; Lulu Zhang; Nannan She; Yunqi Liu; Yongming Chai; Chenguang Liu (359-365).
A compound catalyst (RA) consisted of Ni, ZnO and HZSM-5 with functions of reactive adsorption desulfurization (RADS) and olefin aromatization for fluid catalytic cracking (FCC) gasoline upgrading was prepared. X-ray powder diffraction (XRD), temperature-programmed reduction and low-temperature N2 adsorption were used to characterize the properties of the catalysts. Performance evaluation by FCC gasoline was carried out, and the result showed that the catalyst RA performed well in desulfurization and aromatization. For comparison, RADS catalyst (represented by DS) consisted of Ni and ZnO and aromatization catalyst (represented by Ar) consisted of HZSM-5 were prepared, respectively. They were combined in different ways to help investigating interaction between Ni and HZSM-5. Performance evaluated by FCC gasoline showed that catalyst RA performed best in desulfurization with a slight octane number loss. Interaction between Ni and HZSM-5 is a significant factor which influences the performance of the catalyst.
Keywords: Gasoline; Reactive adsorption desulfurization; Aromatization; Coupling; Interaction

The application of mesoporous alumina with rich Brönsted acidic sites in FCC catalysts by Rui Feng; Peng Bai; Songtao Liu; Peng Zhang; Xinmei Liu; Zifeng Yan; Zhongdong Zhang; Xionghou Gao (367-372).
To decrease the coke yield while increase the conversion of FCC feedstock is of great significance as the crude oil becoming heavier and poorer in quality. In this work, the modified mesoporous alumina with rich Brönsted acidic sites (BAS) and reduced Lewis acidic sites (LAS) have been prepared by a sol-gel method. The modified γ-Al2O3 was characterized by X-ray diffraction, N2 sorption and FT-IR analysis and then used as the binder in FCC catalyst for catalytic activity tests. The results showed that the modified γ-Al2O3 (M-2) possessed a high BAS/LAS pyridine-IR band ratio of 0.75. The new catalysts with modified γ-Al2O3 (New-2) showed a good performance in increasing conversion of FCC feedstock by 8.55 % but reduced the coke yield by 3.25 % compared with catalyst of commercial alumina sol binder (C-AS). Besides, the New-2 increased the gasoline yield and diesel yield by 7.02 and 3.02 %.
Keywords: Brönsted acidic sites; Mesoporous alumina; Coke formation; FCC

An efficient modification of ultra-stable Y zeolites using citric acid and ammonium fluosilicate by Ke Qiao; Xuejin Li; Lifeng He; Xinmei Liu; Zifeng Yan; Wei Xing; Lihong Qin; Baoqin Dai; Zhihua Zhang (373-378).
The modification of commercial ultra-stable Y (USY) zeolite using citric acid (CA) and ammonium fluosilicate (AFS) was investigated. A series of factors including the concentration of CA and AFS, the volume ratio of CA and AFS, adding rate of AFS, reaction time and temperature were studied to get the optimum operation condition. The pore structure, acid property and crystal structural of modified USY zeolite were characterized by a variety of means such as N2 adsorption, Fourier transform infrared spectroscopy, NH3-temperature programmed desorption and X-ray diffraction. The as-synthesized sample presents an increased secondary pore volume up to 0.20 cm3/g which accounts for 46.5 % of the total pore volume, and appropriate acidity distribution as well as good crystallinity. In addition, the modified USY zeolite possesses a superhigh Si/Al ratio of 25.7 which is more than twice higher than that of commercial USY zeolite. Furthermore, the hydrothermal stability of the modified samples meet the requirements of commercial catalysts for hydrocracking. Performance evaluation was carried out on a 200 mL fixed-bed single stage hydrogenation unit using Daqing VGO as feedstock. The 140–370 °C middle distillate yield is 67.78 %, and middle distillate selectivity can reach up to 80.76 %. Compared with commercial catalyst, the yield and selectivity are increased by 7.36 and 4.38 %, respectively.
Keywords: USY zeolite; Modification; Citric acid; Ammonium fluosilicate

The development of FCC catalysts for producing FCC gasoline with high octane numbers by Zhongdong Zhang; Zhaoyong Liu; Rui Feng; Pusheng Liu; Zifeng Yan (379-383).
The effects of acidity and pore properties of rare earth modified USY on heavy oil conversion were investigated. USY with varied rare earth contents were prepared with impregnation method. FCC catalysts were also prepared with modified USY and tested by micro activity tests (MAT) and advanced catalytic evaluation (ACE). The results showed that USY3 had a good performance in cracking polycyclic hydrocarbons in heavy oil and diesel to aromatics and iso-olefins that exist in gasoline; the surface area and pore volume of USY3 increased by 54 m2/g and 0.032 ml/g, respectively, after porosity cleaning; the new optimized FCC catalysts improved the cracking of polycyclic aromatic hydrocarbons (PAHs) to form gasoline with high octane numbers. When tested on a pilot riser unit at 500 °C and 1.89 s with a catalyst-to-oil ratio of 5.6, the new catalyst Cat-3 had a 0.24 % higher propylene yield and a 1.52 % higher liquid yield compared with the reference catalyst Cat-1. However, it had a 7.89 % lower olefin content in FCC gasoline with the same octane numbers.
Keywords: USY; Pseudo-boehmite; Aluminum debris; Octane number; Olefin

Research on the high activity of REY zeolite in fluid catalytic cracking reaction by Zhaoyong Liu; Zhongdong Zhang; Hongchao Fan; Yi Wang; Pusheng Liu; Chaohe Yang (385-388).
In this paper, a novel REY zeolite, modified with rare earth through short process of preparation technology and rare earth location technology was introduced. Compared with routine REY zeolite, micro-activity test (MAT) conversion of the novel REY increased by 18 % at least. The catalytic cracking performances of the catalysts were tested on a fixed-fluid-bed bench unit. The results showed that when compared with CAT-old, the conversion of CAT-new catalyst increased by 1.60 % and heavy oil yield decreased by 0.23 %; the total liquid and light oil yield increased by 1.01 and 0.55 %, respectively. Motor octane number and research octane number of gasoline produced by CAT-new sample have increased 0.1 and 1.0 unit, respectively. Therefore, it has good application prospect and remarkable economic benefit.
Keywords: Y zeolite; Rare earth; MAT conversion; Catalyst; FCC

Synthesis of meso-SAPO-11 and its enhancement of isomerization in fluid catalytic cracking process by Hao Song; Zhen Liu; Wei Xing; Rui Feng; Zifeng Yan; Lianhong Zhao; Zhongdong Zhang; Xionghou Gao (389-394).
With the quality of crude oil becoming worse, the efficient Fluid catalytic cracking (FCC) conversion of heavy oil is of great challenge. The enhancement of isomerization during catalytic cracking process is a feasible approach to improve the gasoline yield and quality. In this study, meso-SAPO-11 was synthesized by citric acid modification to generate mesopores in the SAPO-11 molecular sieve. The modification temperature played an important role in the mesopore generation. Nitrogen sorption and X-ray diffraction analysis had been utilized to characterize the mesoporous structure. Meso-SAPO-11 was further used as an additive in the FCC catalyst for catalytic evaluation with atmospheric gas oil and coking gas oil. The additive showed significant improvement of heavy oil conversion, especially for the gasoline yield and quality .
Keywords: Meso-SAPO-11; Fluid catalytic cra; Heavy oil; Isomerization; Gasoline

Multifunctional two-stage riser fluid catalytic cracking process by Jinhong Zhang; Honghong Shan; Xiaobo Chen; Chunyi Li; Chaohe Yang (395-400).
This paper described the discovering process of some shortcomings of the conventional fluid catalytic cracking (FCC) process and the proposed two-stage riser (TSR) FCC process for decreasing dry gas and coke yields and increasing light oil yield, which has been successfully applied in 12 industrial units. Furthermore, the multifunctional two-stage riser (MFT) FCC process proposed on the basis of the TSR FCC process was described, which were carried out by the optimization of reaction conditions for fresh feedstock and cycle oil catalytic cracking, respectively, by the coupling of cycle oil cracking and light FCC naphtha upgrading processes in the second-stage riser, and the specially designed reactor for further reducing the olefin content of gasoline. The pilot test showed that it can further improve the product quality, increase the diesel yield, and enhance the conversion of heavy oil.
Keywords: Fluid catalytic cracking; Two-stage riser; Gasoline upgrading; Diesel; Heavy oil

Preparation of hierarchical SAPO-11 molecular sieve and its application for n-dodecane isomerization by Hao Song; Zhen Liu; Wei Xing; Zhipeng Ma; Zifeng Yan; Lianhong Zhao; Zhongdong Zhang; Xionghou Gao (401-407).
The isomerization conversion of long chain paraffins for high quality lube oil production plays an important role in the petrochemical industry. The conventional isomerization catalyst, SAPO-11 molecular sieve, exhibits disadvantages for large molecule transfer and multi-branched isomer conversion. To overcome the difficulty of long chain paraffin isomerization, SAPO-11 with hierarchical structure was synthesized by acid modification. With comparison of citric acid modification and hydrochloride acid modification, the hierarchical SAPO-11 was obtained and characterized by nitrogen sorption, XRD, SEM, TEM, and Py-FTIR. The catalytic isomerization activity of prepared hierarchical SAPO-11 was evaluated by n-dodecane isomerization reaction, and the results showed that it had high isomerization conversion and multi-branched isomer selectivity.
Keywords: Isomerizationn-Dodecane; SAPO-11; Hierarchical structure

Deep hydrodesulfurization (HDS) of gas oils continues to attract research interest due to environmental-driven regulations which limit its sulfur content to 10–15 ppm in several countries. This paper highlights some of the recent studies conducted at King Fahd University of Petroleum and Minerals to develop improved HDS catalysts. The first study was focused on the effect of Co/(Co + Mo) ratio in CoMo/Al2O3 catalysts on HDS pathways of benzothiophene (BT) and dibenzothiophene (DBT). Co/Co + Mo ratio exhibited significant influence on the direct desulfurization (DDS) pathway, but showed no influence on the hydrogenation pathway. A Co/Co + Mo ratio of 0.4 exhibited optimum promotion effect of Co for HDS by DDS route and hence overall HDS. The second study investigated the effect of phosphorus addition on simultaneous HDS reactions and their pathways. The results indicate that phosphorus modification of CoMo/γ-Al2O3 catalysts resulted in enhancement of HDS due to increased dispersion of MoO3 and the maximum enhancement was achieved with 1.0 wt % P2O5. Enhancement of HDS rates was in the following order: 4,6-DMDBT (51 %) > 4-MDBT (38 %) > DBT (26 %). In the third approach, a series of NiMo catalysts supported on Al2O3-ZrO2 composites containing 0–10 wt % ZrO2 was synthesized, characterized and evaluated for deep desulfurization of gas oil. An increase of 1.3–2.5 times increase in HDS activity at 320–360 °C was observed due to reduced interaction between Al2O3 and the active metals. A correlation was found between the enhancement of hydrogenation activity of sulfided catalysts and the reducibility of their oxide precursors.
Keywords: Arabian gas oils; Hydrodesulfurization; HDS pathways; CoMo/Al2O3NiMo/Al2O3-ZrO2

In this study, the classes and structures of nitrogen species in coker gas oil (CGO) are characterized by electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) combined with Fourier transform infrared (FT-IR) spectroscopy. The results demonstrate that the m/z of basic and non-basic nitrogen compounds ranges from 180 to 560 and from 200 to 460, respectively. Six basic nitrogen compounds, N1 (a molecule contains one nitrogen atom, similarly hereinafter), N1O1, N1O1S1, N1O2, N1S1, and N2, are identified by their positive-ion mass spectra, and four non-basic nitrogen compounds, N1, N1O1, N1S1, and N2, are characterized by their negative-ion mass spectra. Among these nitrogen compounds, the N1 class species are the most predominant. Combined with the data of ESI FT-ICR MS and FT-IR, the basic N1 class species are likely pyridines, naphthenic pyridines, quinolines, and benzoquinolines. The most non-basic N1 class species are derivatives of benzocarbazole. The N2 class species are likely amphoteric molecules with pyridine and pyrrole core structures.
Keywords: Nitrogen compounds; Coker gas oil; ESI FT-ICR MS; FT-IR; Characterization

An integrated methodology for the modeling of Fluid Catalytic Cracking (FCC) riser reactor by Yu Peng Du; Qi Yang; Hui Zhao; Chao He Yang (423-433).
Modeling description of the riser reactor is a highly interesting issue in the development of FCC process. However, one of the challenging problems in the modeling of FCC riser reactors is that sophisticated flow-reaction models with high accuracy need long computational time, while simple flow-reaction models give rise to results with fast computation but low accuracy. This dilemma requires new type of coupled flow-reaction models. The goal of this study was to propose a novel integrated model with time-efficient computation and acceptable accuracy. The integrated model, named equivalent reactor network (ERN) model, was established based on Aspen Plus simulator with considering gas–solid hydrodynamics via built-in modules and catalytic reactions via external FORTRAN subroutines, as well as lump mixtures characterized by real components. Through comparing with pilot-scale experimental data and industrial plant data in two case studies, the developed ERN model was justified to be capable of precisely and quickly modeling FCC riser reactors. Furthermore, the proposed methodology is expected to be readily applied to studies on the dynamic simulation, optimization, and control of FCC units in future studies.
Keywords: Equivalent reactor network (ERN); Aspen plus; Riser reactor; FORTRAN subroutine; Integrated model

Advances of two-stage riser catalytic cracking of heavy oil for maximizing propylene yield (TMP) process by Yang Chaohe; Chen Xiaobo; Zhang Jinhong; Li Chunyi; Shan Honghong (435-439).
Two-stage riser catalytic cracking of heavy oil for maximizing propylene yield (TMP) process proposed by State Key Laboratory of Heavy oil Processing, China University of Petroleum, can remarkably enhance the propylene yield and minimize the dry gas and coke yields, and obtain high-quality light oils (gasoline and diesel). It has been commercialized since 2006. Up to now, three TMP commercial units have been put into production and other four commercial units are under design and construction. The commercial data showed that taking paraffinic based Daqing (China) atmospheric residue as the feedstock, the propylene yield reached 20.31 wt%, the liquid products yield (the total yield of liquefied petroleum gas, gasoline, and diesel) was 82.66 wt%, and the total yield of dry gas and coke was 14.28 wt%. Moreover, the research octane number of gasoline could be up to 96.
Keywords: Two-stage riser; Catalytic cracking; Propylene

HS-FCC High-severity fluidized catalytic cracking: a newcomer to the FCC family by R. S. Parthasarathi; Sarah S. Alabduljabbar (441-444).
High-severity fluid catalytic cracking (HS-FCC) is a breakthrough technology in the refining and petrochemicals industry. It allows refineries to produce petrochemicals from heavy oils by converting a low-value refinery stream into high-value products, suitable for integrated processes. The process’s main operating features are the down flow reactor system, high reaction temperature, short residence time, and high catalyst-to-oil (C/O) ratio with a modified separator system. The unique down flow reactor system in the HS-FCC process ensures plug flow without back-mixing, allowing more selectivity toward light olefins. HS-FCC produces four times more light olefins (propylene and butene) and higher octane gasoline than conventional FCC units. Since 1999, the HS-FCC has successfully passed several phases of testing with different types of feedstock at various feed capacities. The process has been proven in a 30 barrel per day (bpd) demonstration plant at Ras Tanura Refinery, Saudi Arabia. In 2011, a 3,000 BPD HS-FCC semi-commercial plant started operating at JX Mizushima Refinery in Japan. The unit ran successfully, meeting all design objectives. A full-scale commercial unit study for a 30,000 BPD HS-FCC plant was completed by JX and Chiyoda for HS-FCC commercialization.
Keywords: Fluid catalytic cracking; High-severity; Down flow reactor; Light olefins; Propylene