Raffinate Oil Research Articles

Experimental Study on Enrichment of Indole in Wash Oil by a Combined Process of Extraction and Re-Extraction

Wash oil, one of the by-products of coal tar distillation, contains useful nitrogen heterocyclic compounds (NHC) such as indole (IN), which is used as a raw material for perfume, essential amino acid, and pharmaceuticals. In this study, as a pre-treatment step for purification of IN, which is about 5.75% contained in wash oil, the enrichment of IN in wash oil was examined by combining formamide extraction (FE) and n-hexane re-extraction (HRE). The raw material for the re-extraction was a mixture of the preceding formamide extract phase acquired through batchwise 5-stage co-current extraction trial under fixed FE condition. As the 5-stage FE and HRE progressed, the IN yield based on IN in the wash oil was approximately 73.3%, and the IN concentration in the raffinate oil acquired from the re-extraction run was highly enriched to about 92.4%. In addition, the IN enrichment efficiency of the FE-HRE combined process (FHC) employed in this study was compared with methanol extraction (ME)-hexane re-extraction (HRE) combination (MHC).

Study of aromatic extraction from light cycle oil from the viewpoint of industrial applications

Light cycle oil (LCO) is a significant products of fluid catalytic cracking (FCC) process in refineries. Increasing the output of high-value chemicals from LCO is an important step towards achieving ‘dual carbon’ targets. Separating aromatic and non-aromatic components in LCO is crucial to producing valuable products. Extraction is a promising process for separating these components based on the principle of “polar similarity and solubility”. From the perspective of industrial applications, this study explores the development and application of novel functionalized extractants to produce valuable products. Ionic liquids (ILs) with alkyl-substituted imidazoles [CnMIM]+ and alkyl-substituted pyridines [CnMPy]+ as cations and tetrafluoroborate [BF4]− and hexafluorophosphate [PF6]− as anions were used. The effects of extraction temperature, IL-oil ratio, number of extraction stages, and reusability were systematically investigated. In addition, the basic physical properties data of ILs and residues in oil were studied in detail. The suitability of ionic liquids for industrial applications was evaluated based on their solubility with hydrocarbons, physical and chemical properties, selectivity for aromatics, and residues in oil. Following a thorough examination of the performance of ionic liquids for the extraction of aromatics from LCO, [C6MIM][PF6] was identified as the most suitable extractant. A multi-stage countercurrent extraction process was established and the conditions systematically studied. The results demonstrate that the aromatic content of the extracted oil is greater than 95 wt%, which can be utilized for producing BTX products. Meanwhile, the aromatic content of the raffinate oil is less than 10 wt%, which can function as a clean diesel blending component or as steam cracking feedstocks. This study has successfully promoted the industrial application of functionalized ionic liquids for the LCO dearomatization process and provided an essential reference for developing new functionalized extraction solvents.

Study on efficient utilization of light cycle oil with combined process

ABSTRACT A combined process of hydrotreating, fractionating, solvent extraction, and fluid catalytic cracking (FCC) was proposed to improve the added value of light cycle oil (LCO). In the process, hydrotreating LCO (HLCO) was divided into light and heavy fractions by fractionating. The bicyclic and tricyclic aromatics in the heavy fraction of HLCO were extracted to produce chemical products by solvent extraction. The raffinate oil and the light fraction of HLCO, rich in saturated hydrocarbons and monocyclic aromatic hydrocarbons, were processed to produce high-octane gasoline by FCC. According to the results, the combined process solved the problem of polycyclic aromatic hydrocarbons of HLCO being challenging to be cracked in FCC reaction, reduced the yield of dry gas and coke by 43.01 wt%, reduced the yield of diesel with low added value by 32.33 wt%, and optimized the product structure. In other words, the process makes efficient use of the aromatic and nonaromatic components in LCO.

Autothermal Reforming of Volatile Organic Compounds to Hydrogen-Rich Gas

Industrial emissions of volatile organic compounds are urgently addressed for their toxicity and carcinogenicity to humans. Developing efficient and eco-friendly reforming technology of volatile organic compounds is important but still a great challenge. A promising strategy is to generate hydrogen-rich gas for solid oxide fuel cells by autothermal reforming of VOCs. In this study, we found a more desirable commercial catalyst (NiO/K2O-γ-Al2O3) for the autothermal reforming of VOCs. The performance of autothermal reforming of toluene as a model compound over a NiO/K2O-γ-Al2O3 catalyst fitted well with the simulation results at the optimum operating conditions calculated based on a simulation using Aspen PlusV11.0 software. Furthermore, the axial temperature distribution of the catalyst bed was monitored during the reaction, which demonstrated that the reaction system was self-sustaining. Eventually, actual volatile organic compounds from the chemical factory (C9, C10, toluene, paraxylene, diesel, benzene, kerosene, raffinate oil) were completely reformed over NiO/K2O-γ-Al2O3. Reducing emissions of VOCs and generating hydrogen-rich gas as a fuel from the autothermal reforming of VOCs is a promising strategy.

Retrofit of an industrial solvent recovery system: Distillation sequence intensification and simulation-based optimization

An industrial solvent recovery system in a rubber process consists of four distillation columns to recover solvent and unreacted 1,3-butadiene monomer. After the solvent is changed from raffinate oil to hexanes, it needs to investigate whether the current system can be retrofitted to reduce the number of columns and save energy. This work presents stepwise retrofit of the solvent recovery system by distillation sequence intensification and simulation-based optimization. Based on insights in distillation columns, an evolutionary strategy is introduced to generate intensified distillation sequences from the current distillation system. Next, a simulation-based optimization method considering comprehensive hydraulic evaluation is developed to obtain the best operating parameters of distillation columns. Seven distillation sequence alternatives to the current solvent recovery system are generated. The result indicates that the most compact sequence with two distillation columns can decrease the energy cost by 41.50%, while the preferred solution is a three-column sequence with the least modifications that reduces the energy cost by 33.13%. The proposed method also gives insights in energy saving and identifies bottlenecks to further improve the energy performance.

Kinetics on the Integration of Methanol Aromatization with Raffinate Oil over ZSM-5/ZSM-11 Zeolite

Kinetics on the Integration of Methanol Aromatization with Raffinate Oil over ZSM-5/ZSM-11 Zeolite

Study on the co-carbonization behavior of high-temperature coal tar pitch and raffinate oil of low-temperature coal tar

In needle coke industry, the raffinate oil from raw material refining could be used for co-carbonization to improve the structural evolution of aromatic feedstock with high aromaticity and low alkyl side chain content. High-temperature coal tar pitch (HCTP) and raffinate oil obtained from low-temperature coal tar (LCT) were used to prepare needle coke by liquid phase carbonization, and the characteristics of carbonization behavior as well as the structural evolution of blended materials were also investigated. The raffinate oil possessed abundant saturated compositions and the aromatic component distribution mainly concentrated in 1–3 cyclic aromatic hydrocarbons which resulted in a low yield of derived products and the carbonaceous sheets with poor planarity. Raffinate oil provided sufficient small molecular volatiles of alkyl radicals and generated abundant active sites for the polycondensation of HCTP with high aromaticity and low alkyl side chain content during co-carbonization. The addition of raffinate oil in HCTP facilitated the elimination of steric hindrance and healed the structural defects within the planar aromatic lamellae. This paper improved the utilization of raw material refining treatment and optimized the industrial structure of the needle coke preparation process.

Upgrading of Wash Oil through Reduction of Nitrogen-Containing Compounds

As part of improving the quality of wash oil, the reduction of three kinds of nitrogen-containing compounds (NCs), including quinoline (QU), iso-quinoline (IQU), and indole (IN), found in wash oil was examined by liquid–liquid equilibrium extraction. The wash oil and an aqueous solution of formamide were used as the raw material and the solvent, respectively. Increasing the volume fraction of water in the solvent in the initial state (yw,0) resulted in a decrease in the distribution coefficients of each NC, while inversely, the selectivity of each NC in reference to 2-methylnaphthalene increased. The selectivity ranges of QU, IQU and IN at yw,0 = 0.05~0.3 were 19~57, 19~56 and 50~79, respectively. Through five stages of equilibrium extraction performed under the condition of yw,0 = 0.05, the concentrations of QU and IQU contained in the raffinate oil recovered at the fifth stage were reduced by about 69% and 65% compared to those contained in the wash oil. The concentration of IN in particular, a useful compound in the chemical industry, which is a raw material for pharmaceuticals, dyes, and fragrances, was reduced by 93.4% through a five-stage extraction operation. The formamide extraction method of this study was highly efficient in reducing the NC present in the wash oil, showing the feasibility of this method.

High-Performance n -Hexane Purification by Nonporous Adaptive Crystals of Leaning Pillar[6]arene

The production of high-purity n-hexane under mild conditions is of great significance in both the petrochemical industry and synthetic chemistry. Here, we report an easy-to-operate and energy-effic...

Catalytic co-aromatization of methane and heptane as an alkane model compound over Zn-Ga/ZSM-5: A mechanistic study

The joint conversion of methane and heptane, a model compound of paraffin-rich raffinate oil, over a Zn-Ga modified zeolite catalyst has been investigated at various reaction times. In comparison with the performance from a N2 environment, the introduction of methane highly promotes the formation of light aromatic compounds with a single phenyl ring, and increased carbon number and substitution index of chemical constituents formed are indicative of methane incorporation into the liquid product. In addition, with prolonged time, the interaction between catalyst and methane molecules is enhanced. Through cleavage of methane molecules, the formed moieties likely participate in the aromatization reaction, which results in the growth of larger aromatic components through further condensation. According to the NMR spectra, witnessing methane engagement into the phenyl carbon and alkyl carbon sites of the formed liquid aromatics along with increasing reaction time is evidenced 13C-methane incorporation into aromatics. The excellent catalytic performance of Zn-Ga/ZSM-5 might be ascribed to the greatly dispersed metal species on the catalyst surface as well as a certain amount of medium and weak acid sites. With regards to the spent catalyst, the presence of methane could inhibit the aggregation of loaded active metals and coke formation during the co-aromatization process. The elucidation on the co-conversion of methane and high alkane provides great potential for the utilization of natural gas resources and intermediates formed from petrochemical industries.

Investigation on the light alkanes aromatization over Zn and Ga modified HZSM-5 catalysts in the presence of methane

The catalytic co-aromatization of methane and paraffin-rich raffinate oil was investigated along with hexane, heptane and octane as its model compounds over zinc and gallium modified ZSM-5 zeolite catalysts. The benzene, toluene and xylene (BTX) components derived from light alkane aromatization were highly promoted with the assistance of methane. The co-existence of Zn and Ga metal species has a positive effect on the formation of BTX components, whereas the individual metal loaded catalyst resulted in the production of heavy aromatics, suggesting that zinc and gallium have a synergistic effect on the formation of BTX under the methane environment. When concerned with gaseous analysis, the introduced methane might interact with smaller intermediates and then transform into larger hydrocarbons. From the DRIFT observation, it was witnessed that the interaction between light alkane and methane occurred on the surface of the charged Zn-Ga/ZSM-5 catalyst. According to the comprehensive catalyst characterizations, the excellent catalytic performance may be closely associated with greatly dispersed metal species on the zeolite support, improved microporous characteristic, moderate Brönsted and increased Lewis acidic sites during the paraffin-rich liquid feedstock aromatization under methane environment. This research provides a promising pathway for the highly effective and profitable utilization of petrochemical resources and natural gas.

Multicycle Investigation of Normal Paraffin Separation from Naphtha To Improve Olefin and Aromatic Feed

A programmed control double-column adsorber was built to investigate the steady operation of the normal paraffin separation from naphtha. The naphtha from Shanghai Gaoqiao Petrochemical Company (SGPC) was separated into a raffinate oil rich in non-normal hydrocarbons and a desorption oil rich in normal paraffins, using zeolite 5A as an adsorbent. In this paper, we investigate the effects of the adsorption/desorption temperature, feed space velocity, desorption gas space velocity, and switch time on the steady separation of normal paraffins. The adsorbability observed from the breakthrough curves of normal paraffins is consistent with the adsorption energies. The optimal conditions for the adsorption/desorption process were an operation temperature of 270 °C, a naphtha feed space velocity of 90.1 h–1, a switch time of 30 min, a desorption gas N2 space velocity of 127.5 h–1, and an intermediate oil cutting time of 2 min. With the Cutting Intermediate Oil (CIO) process, the normal paraffin content in raffinate oil was 3.42% and the potential aromatic content was 12.14% higher than that of naphtha. The normal paraffin content of desorption oil was 96.61%, and the ethylene yield was 15.08% higher than that of naphtha.

Preparation of High-Purity Normal Hexane from Reformate Raffinate by Adsorption and Distillation Processes

In this study, a combination process of adsorption and distillation was adopted to obtain high-purity normal hexane. In the adsorption separation process, 5A zeolite was used as the adsorbent and the Shanghai Gaoqiao Petrochemical Corporation reformate raffinate containing 24.24 wt% normal hexane was separated into adsorption raffinate oil rich in non-normal paraffins and desorption oil rich in normal paraffins. At pre-specified operation conditions, concentration of n-hexane in the desorption oil reached higher than 96%. The concentrations of 3-methyl pentane and methyl cyclopentane, which are the light- and heavy-key components in the distillation tower of normal hexane, were reduced to 0.15% and 0.07%, respectively. According to the simulation results obtained using the software Aspen Plus, when the distillation tower has 15 stages, the n-hexane concentration can reach 99.02% with a recovery rate of 72.89% at the reflux ratio of 7.5. The combination process involving both adsorption and distillation ha...

Optimization and Evaluation of Preparation Process of Activated Carbon Loaded ZrO<sub>2</sub> Catalyst for Oxidative Desulfurization

This paper studied how DBT oxidation was influenced by different preparation conditions of diesel desulfurization catalyst. Fuel oil oxidation and desulfurization technology has been studied by using solid superacid prepared by activated carbon loaded SO42-/ ZrO2 as catalyst instead of the traditional liquid acid, hydrogen peroxide as oxidant, in mild conditions. Impacting factors on removal sulfur have been investigated such as soaking time, burning temperature, burning time, active ingredient content and concentration of sulfuric acid, etc. The results show that soaking time is 6h, burning temperature is 500 °C, burning time is 2.5h, the mass ratio of the active ingredient is 3:100 ZrO2 and activated carbon, sulfuric acid concentration is 0.5mol/L. The desulfurization rate is over 93% and raffinate oil recovery can reach more than 86% under this optimum condition.

Optimal Operation of Simulated Moving Bed Technology on Utilization of Naphtha Resource

Simulated moving bed (SMB) technology has attracted more and more attention in recent decades. The simulated moving bed (SMB) technology on optimal utilization of naphtha resource was studied in this paper. A simulated moving bed equipped with 16 columns was used to separate normal paraffins from naphtha. The effects of temperature (T), switching time (ts), extract oil flow rate (LAD), feed flow rate (LF), and desorbent flow rate (LD) on the separation performance were investigated, and the desorbent recycle process was simulated by Aspen Plus. The results showed that the optimal conditions for simulated moving bed were operation temperature (T) of 170°C, switching time (ts) of 900 s, extract oil flow rate (LAD) of 10 mL/min, feed flow rate (LF) of 5 mL/min, and desorbent flow rate (LD) of 20 mL/min. Through the SMB and the desorbent recycle system, the purity of the de-solvent extract oil (DEO) reached 98% and the purity of the de-solvent raffinate oil (DRO) reached 92%, which were the high-quality feed for the ethylene cracking process and the catalytic reforming process, respectively.

STUDIES ON FUSHUN SHALE OIL FURFURAL REFINING

Solvent refining of Fushun shale oil with furfural as a solvent extraction agent was investigated. The results showed that raffinate yield decreased with either the increasing of agent/oil mass ratio or reaction temperature; the extract yield increased under the same conditions, while the quality of raffinate oil was better. At agent/oil mass ratio of 3/1, reaction temperature of 60 °C and residence time of 30 min, the raffinate yield was 55.37%, and the extract yield 43.60%. The heavy component from the extract oil was used for blending different grades of asphalt such as heavy-traffic paving asphalt and building asphalt, the light component from the extract oil was used for separation of non-hydrocarbon compounds; a range of light fuel oil was produced through catalytic cracking experiment with the denitrified raffinate oil, the removed nitrogen compounds were also used for separation of nonhydrocarbon compounds.

Separating group compositions in naphtha by adsorption and solvent extraction to improve olefin yields of steam cracking process

In order to improve the steam cracking feeds, several model compounds including normal paraffins, iso-paraffins, cyclanes and aromatics were selected as the feeds of steam cracking process and the olefin yields were investigated. In the typical reaction conditions, the normal paraffins in the naphtha contribute most to the ethylene in the products; the iso-paraffins are the main sources of the propylene; the cyclanes mainly produce the butadiene and the aromatics can hardly produce olefins. According to this, the adsorption process and solvent extraction process were adopted to separate the group compositions in naphtha properly to optimize the cracking feeds. The n-paraffins in naphtha were gathered through adsorption process using 5A molecular sieves. The ethylene yield improved by 13% using the desorption oil rich in n-paraffins as the cracking feed. The aromatics and the cyclanes were extracted from the naphtha. Compared with the naphtha, the ethylene and propylene yields of the extraction raffinate oil were 3.0 and 1.5% higher respectively.

Adsorption Separation and Use of Normal and Iso-hydrocarbons in Hydrogenated Coking Gasoline

To improve the use efficiency of hydrogenated coking gasoline and to use the hydrocarbon components properly, the AQ hydrogenated coking gasoline was separated into the raffinate oil rich in non-normal hydrocarbons and the desorption oil rich in normal paraffins through the fixed-bed adsorption process using 5A molecular sieves. The adsorption breakthrough curves of normal paraffins were investigated. In comparison to the hydrogenated coking gasoline, the aromatic potential content and the research octane number (RON) of the raffinate oil rose by 14% age points and 30 units, respectively. As a result, the raffinate oil is more suitable to be used as the feed of the catalytic reforming process or the blending component of high-octane gasoline. In similar conditions, the ethylene yield of the steam cracking process using the desorption oil as feedstocks increased 11% age points compared to the hydrogenated coking gasoline feed.

Optimizing the Utilization of Natural Gas Condensate through the Separation of n-Paraffins

To improve the utilization efficiency of gas condensate and effect the proper use of the hydrocarbon components, AKS gas condensate was separated, through the use of a fixed-bed adsorption process employing 5A molecular sieves, into the raffinate oil which is rich in non-normal hydrocarbons and the desorption oil which is rich in n-paraffins. The adsorption breakthrough curves of n-paraffins were investigated. Relative to the gas condensate, the aromatic potential content and the research octane number (RON) of the raffinate oil increased by 12.9% and by over 20 units, respectively. As a result, the raffinate oil is more suitable for use as the feedstock in the catalytic reforming process and as the blending component of high-octane gasoline. Under similar conditions, the ethylene yield of the steam cracking process using the desorption oil as the feedstock increased by 6.5% compared to the situation when the gas condensate was employed as the feedstock.

Optimizing Naphtha Utilization Based on Molecular Scale Management

The technology of separating normal paraffins from naphtha through adsorption using 5A molecular sieves was studied. The separation efficiency of the normal paraffins was above 99.99%. Using the desorption oil as the feedstock of steam cracking, the ethylene yield increased from 29.7–35.0% to 41.4–49.2% compared to that of the naphtha. The research octane number of the raffinate oil reached more than 85 units with an increase of 20 units compared to that of naphtha.