Catalysts
·
2022
·Vol. 12
·期 6
·640
·
IF 4.501
Xu Lu,Chenhao Wei,Liang Zhao,Jinsen Gao,Chunming Xu
Coke formation on n-butene cracking catalyst is the main reason for the reducing of its lifetime. To study the effects of acidity and textural properties on the coke formation process, a series of HY zeolite-type catalysts were prepared by ammonium hexafluorosilicate treatment (AHFS). NH3-TPD and Py-IR-TPD were used to systematically study the change law of zeolite acidity. It was found that with the increase of AHFS concentration, the acid density decreased, whereas the ratio of Brønsted acid to Lewis acid first increased and then decreased. Meanwhile, the percentage of Brønsted acid inside the supper cages increased and the strength of Brønsted acid increased with the degree of dealumination. Combined with in situ IR study on coke formation, the relationship between coking and acid site was revealed. It was found that the rate of coke formation on zeolites was affected by acid density, which is the rate of coke formation decreased with the decline of acid density. When the acid density remains at the same level, it was the acid strength that determined the coke formation rate—the stronger the acid strength, the faster the coke formation rate.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2025
·
IF 6.2
Xiaoning Zhang,Buning Chen,Jianwei Wang,Yusheng Zhou,Xueli Huang,He Huang
The high tolerance to feed oil makes slurry bed hydrocracking technology one of the main streams of research, but the relationship between hydrogenation and deactivation of slurry bed catalysts remains unclear. In this study, the distribution of vacuum residue (VR) hydrogenation products, coke generation, and catalyst deactivation patterns were analyzed using MoS 2 /TiO 2 as the hydrogenation catalyst. With an increase in the reaction temperature or decrease in the hydrogen pressure, the cracking performance gradually improved, the hydrogenation saturation effect gradually weakened, and the oil-to-coke ratio (OCR) gradually decreased. This implies that the influence of the lightning effect from coke generation gradually increased. The conversion rate of VR to gasoline and diesel components is 3.8 times higher than the conversion rate to coke and gas. At lower temperatures, coke was dominated by graphitic carbon encapsulated on the catalyst surface. As the temperature increased, the content and lamellar diameter of graphitic carbon decreased, and the content of amorphous carbon increased. An increase in temperature also promoted the dealkylation reaction and coke condensation, resulting in a decrease in pyrolytic activity. VR hydrogenation was subjected to kinetic analysis, and a model for MoTi-5-catalyzed VR deactivation was developed using OCR to deduce the degree of contribution of coke generation to lightning.
研究领域:
石油化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Zengtong Deng,Syed Shatir A. Syed-Hassan,Yuanjing Chen,Long Jiang,Jun Xu,Song Hu,Sheng Su,Yi Wang,Jun Xiang
Bio-oil can be converted to chemicals, carbon material, or syngas by various thermochemical processes which are always preceded with the pyrolysis step. In bio-oil pyrolysis, coke formation is almost inevitable, causing difficulties for further processing. In this study, bio-oil was mixed with Ni/Al 2 O 3 before it was fed for pyrolysis. Interesting results were observed whereby the effect of Ni/Al 2 O 3 mixing on coke formation shifted from promoting to inhibiting with increasing pyrolysis temperature. When the temperature was higher than 700 °C, contrary to the cases without mixing, the apparent decreases in coke yield were observed (e.g., the coke yield decreased by 10% at 800 °C). Comparative studies on bio-oil and its lignin-derived oligomer fraction indicated that the catalytic cracking of small molecules could enhance the formation of hydrogen radicals, which promoted thermal decomposition of lignin-derived oligomers, thus inhibiting coke formation via polymerization.
研究领域:
能源科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Scientific Reports
·
2016
·Vol. 6
·期 1
·1-10
·
IF 5.228
Zhang Huiyan,Wang Yun,Shao Shanshan,Xiao Rui
Lignin is the most difficult to be converted and most easy coking component in biomass catalytic pyrolysis to high-value liquid fuels and chemicals. Catalytic conversion of guaiacol as a lignin model compound was conducted in a fixed-bed reactor over ZSM-5 to investigate its conversion and coking behaviors. The effects of temperature, weight hourly space velocity (WHSV) and partial pressure on product distribution were studied. The results show the maximum aromatic carbon yield of 28.55% was obtained at temperature of 650 °C, WHSV of 8 h −1 and partial pressure of 2.38 kPa, while the coke carbon yield was 19.55%. The reaction pathway was speculated to be removing methoxy group to form phenols with further aromatization to form aromatics. The amount of coke increased with increasing reaction time. The surface area and acidity of catalysts declined as coke formed on the acid sites and blocked the pore channels, which led to the decrease of aromatic yields. Finally, a kinetic model of guaiacol catalytic conversion considering coke deposition was built based on the above reaction pathway to properly predict product distribution. The experimental and model predicting data agreed well. The correlation coefficient of all equations were all higher than 0.90.
研究领域:
生物质能
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BioEnergy Research
·
2013
·Vol. 6
·期 4
·1173-1182
·
IF 4.25
Shao Shanshan,Zhang Huiyan,Xiao Rui,Shen Dekui,Zheng Jian
The conversion of three major biomass derivates was conducted in a quartz tubular fixed bed reactor over a ZSM-5 catalyst. As the model compounds of polyols, saturated furans and unsaturated furans, ethylene glycol (EG), tetrahydrofuran (THF) and furan were pyrolyzed to find out the influence of chemical structure on the catalytic characteristics. The effect of pyrolysis temperature (400 ∼ 650 °C), weight hourly space velocity (2.9 ∼ 15.5 h −1 ) and partial pressure (2.12 ∼ 20.49 Torr) on the feed conversion, product yield and selectivity were investigated. The hydrogen to carbon effective ratio (H/C eff ) was referred to, to analyze the capacity of biomass derivates being converted to chemicals (olefins and aromatics). The results showed that the existence of rings and C=C had great effect on the catalytic characteristics. The conversion of furan was much lower (mainly less than 60 %) than that of EG and TH,F which were close to 100 %. It was also found that the chemical yield of THF was slightly more than that of EG, which can be attributed to its relative higher H/C eff of 1.5. Furan produced the highest coke yield, which was more than 15 %, whereas that of EG and THF was only around 5 %. The serious coking of furan led to the lowest chemical yield, which was less than 35 %. This study paves a way for the mechanism study on catalytic characteristics of biomass-derived feedstocks over zeolite catalysts.
研究领域:
能源科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 69
·56286-56292
·
IF 3.84
Bo Zhang,Zhaoping Zhong,Qinglong Xie,Paul Chen,Roger Ruan
In order to reduce coke yield during catalytic fast pyrolysis of biomass, MgO and 2,4-dimethylquinoline (2,4-DMQ) were selected to reduce the number of external acid sites of HZSM-5. Both MgO and 2,4-DMQ deposition could cause a reduction in total acid sites (both weak acid sites and strong acid sites) and external acid sites of HZSM-5. The modified catalysts were used for the catalytic conversion of bio-derived furan. For the MgO/HZSM-5 catalyst, the effects of amount of MgO deposited and deposition time were studied. The carbon yields of aromatics, C2–C5 olefins, total chemicals, CO2 and CO increased at first and then decreased slightly when the deposited amount increased, while the carbon yield of coke decreased first and then increased gradually. Furthermore, as the deposited time increased, the carbon yields of petrochemicals, CO2 and CO increased greatly, whereas that of coke decreased. For the 2,4-DMQ/HZSM-5 catalyst, the effects of 2,4-DMQ treatment amount and treatment time were investigated. The experimental results showed that an increase in 2,4-DMQ treatment amount or treatment time could retard the generation of the target products, CO2 and CO but promote coke formation.
研究领域:
能源化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2025
·
IF 7.5
Fangjun Chen,Jinze Dai,Henrik Ström,Yi Ouyang,Muhammad Shahzad Khurram,Bilainu Oboirien,Lin Lang,Qingang Xiong
The mechanisms by which calcium-rich inorganics within pulp and paper mill sludge (PPMS) influence the pyrolysis of its organic components remain largely unexplored. This study investigated the effects of inorganic constituents on the evolution of pyrolysis products from major organic components (cellulose, plastics, lipids, proteins, and ink) in PPMS through fixed-bed pyrolysis experiments. The results demonstrated that inorganics significantly promoted secondary tar reactions by improving heat transfer, providing catalytic sites, and prolonging the residence time of pyrolysis vapors. These effects markedly increased gas yields, particularly CO 2 (e.g., by 29.27–35.41 mL/g for cellulose), and decreased tar yields (e.g., by 10.27–11.38 wt% for cellulose), while also altering tar composition. Specifically, calcium-rich inorganics catalyzed the conversion of cellulose into small ketone molecules such as hydroxyacetone, reducing the proportions of anhydrosugars and furans. For plastics, PPMS ash promoted the β -scission of long-chain aliphatic hydrocarbons and the transformation of monocyclic hydrocarbons into polycyclic aromatic hydrocarbons while also increasing char formation. For lipids, calcium-rich inorganics effectively catalyzed the decarboxylative ketonization of palmitic acid to produce 2-heptadecanone. For proteins, PPMS ash suppressed NH 3 release and promoted nitrogen migration into nitrogen-containing heterocyclic compounds. For ink, the inherently high ash content limited the regulatory effect of additional ash. Overall, this study provides mechanistic insights into PPMS pyrolysis and supports its sustainable conversion.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2025
·
IF 3.5
Lei Chen,Wenjie Yao,Xu Chen,Gang Yang
The Cu-Ce modified SAPO-34/ZSM-5 (S-Z) composite molecular sieve catalysts were synthesized via a stepwise crystallization process using triethylamine (TEA) and tetraethylammonium hydroxide (TEAOH) as dual templates. This method significantly reduces the crystallization time from 24 hours to 12 hours. The incorporation of metal ions alters the structure and acid strength of the molecular sieves, thereby decreasing the rate of coke formation during the reaction, which in turn extends the catalyst's lifetime. Experimental results demonstrated that the catalyst's lifetime increased progressively with the addition of Ce. In the methanol-to-olefin reaction, the catalytic lifetime of the S-Z/Cu 0.05 -Ce 0.05 samples reached 1440 mins, approximately 480 mins longer than that of the S-Z samples, while maintaining a selectivity for low-carbon olefins at around 89.6%.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2020
·
IF 4.982
Xin Jin,Xiaorong Li,Jiao Kong,Wei Xie,Meijun Wang,Jiancheng Wang,Weiren Bao,Liping Chang
The high yields of coke and tar pitch relating to volatile reactions can cause plug in the product lines during low temperature pyrolysis of low-rank coals. To study the potential transformation of volatile into coke during its migration in the pyrolysis process, six distillates and their blends from the same coal tar were heated at 400–600 °C. The composition , radicals of six distillates and coke structure were characterized by GC × GC–MS, ESR and Raman techniques, respectively. The results show that the coke yields increase with temperature during thermal reaction for all six distillates. When light oil and pitch are blended, the interaction between the two distillates compresses the transformation of volatile into coke above 500 °C. This can be ascribed to that the reactive hydrogen radicals generated from light oil may weaken the bonding between large molecules. By contrast, other distillates (phenolic oil, naphthalic oil, wash oil and anthracene oil) promote coke formation, resulting in higher coke yields than expected. It is also observed that the highest extent of interaction occurs between phenolic oil and pitch, which may be related to the high content of oxygen containing compounds in phenolic oil and the high electron density of the compounds in pitch.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
Results in Engineering
·
2023
·
IF 5
Yeqing Huang,Manna Wang,Yi Huang,Jin Shang,Baoyu Liu
The distribution of Brønsted acid sites in three-dimensional 12-membered pore channels of Beta zeolite was a decisive factor in the alkylation of benzene with cyclohexene. Here, the Brønsted acid site distribution in Beta zeolitic channels was precisely regulated by tuning the content of Na + in crystallization system combined with tetraethylammonium cation, the Beta-55 with Brønsted acid sites exclusively located in straight channels (along a - and b -axis directions) was successfully synthesized by utilizing tetraethylammonium as the structure-directing agents without Na + species, and the fraction of Brønsted acid sites in sinusoidal/straight channels of Beta zeolites can be accurately controlled by tailoring the content of Na + in synthesis gel. Catalytic properties in the liquid alkylation between benzene and cyclohexene exhibited that Beta-55 zeolites with the Brønsted acid sites solely located in a -axis and b -axis channels showed the highest cyclohexene conversion, cyclohexylbenzene selectivity and longest lifetime in this reaction. In addition, the resultant Beta zeolites also exhibited low coke generation rate and robust regeneration performance in the alkylation reaction.
研究领域:
催化
·
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
Biomass Conversion and Biorefinery
·
2022
·
IF 4.05
Su Jing,Miao Kai,Zhao Yuan,Li Tan,Zhao Zhigang,Luo Guanqun,Wang Kaige
Catalytic fast pyrolysis (CFP) of biomass is a promising technology that can convert biomass into fuels. To understand how the metal oxides modified HZSM-5 catalysts enhance the formation of desirable hydrocarbons as well as suppress the coke formation during catalytic pyrolysis of lignocellulosic biomass, three types of metal (molybdenum (Mo), gallium (Ga), and tungsten (W)) oxides modified HZSM-5 catalysts were prepared. The activity of the catalysts was evaluated on a micro-reactor system. The effects of the atmosphere, metal oxide types, loading amounts of metal oxide, and catalysis temperature were all discussed. The introduction of hydrogen significantly enhanced the formation of hydrocarbons and decreased the coke formation. The yield of aliphatic products was further increased by 60%, while coke formation was suppressed by 52% using metal oxide-modified HZSM-5. Among these catalysts, HZSM-5 modified by molybdenum oxide obtained the highest hydrocarbon yield of 49.6%. HZSM-5 modified by gallium oxide obtained the highest aliphatic hydrocarbon yield of 30.4%. Compared to the control test using the HZSM-5 catalyst, coke yields were also decreased by 36%, 38%, and 35% for HZSM-5 modified by molybdenum oxide, gallium oxide, and tungsten oxide, respectively. HZSM-5 modified by molybdenum oxide was selected to further investigate the effects of loading amounts, catalysis temperature, and biomass to catalysts ratio.
研究领域:
化学工程
·
可再生能源
·
催化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）