HZSM-5 zeolites undergoing the high-temperature process for boosting the bimolecular reaction in n-heptane catalytic cracking

High-temperature treatment is key to the preparation of zeolite catalysts.Herein,the effects of hightemperature treatment on the property and performance of HZSM-5 zeolites were studied in this work.X-Ray diffraction,N2physisorption,27Al magic angle spinning nuclear magnetic resonance(MAS NMR),and temperature-programmed desorption of ammonia results indicated that the hightemperature treatment at 650℃ hardly affected the inherent crystal and texture of HZSM-5zeolites but facilitated the conversion of framework Al to extra-framework Al,reducing the acid site and enhancing the acid strength.Moreover,the high-temperature treatment improved the performance of HZSM-5 zeolites in n-heptane catalytic cracking,promoting the conversion and light olefins yield while inhibiting coke formation.Based on the kinetic and mechanism analysis,the improvement of HZSM-5 performance caused by high-temperature treatment has been attributed to the formation of extra-framework Al,which enhanced the acid strength,facilitated the bimolecular reaction,and promoted the entropy change to overcome a higher energy barrier in n-heptane catalytic cracking.

Effect of particle size of single-crystalline hierarchical ZSM-5 on its surface mass transfer in n-heptane catalytic cracking

Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.

Experiment and modeling of coke formation and catalyst deactivation in n-heptane catalytic cracking over HZSM-5 zeolites

Since paraffins catalytic cracking was of significant importance to light olefins and aromatics production,this work was intended to gain insights into the feature and model of coke formation and catalyst deactivation in n-heptane catalytic cracking over HZSM-5 zeolites. 18 tests of n-heptane catalytic cracking were designed and carried out over HZSM-5 zeolites in a wide range of operating conditions. A particular attention was paid to the measurement of the conversion, product distribution, coke content, and the porosity and acidity of the fresh and spent HZSM-5 zeolites. It was found that alkene and aromatic promoted coke formation, and it reduced the pore volume and acid site of HZSM-5 zeolites, tailoring its performance in n-heptane catalytic cracking. The specific relationship between HZSM-5 zeolites, n-heptane conversion, product distribution and coke formation was quantitively characterized by the exponential and linear function. Based on the reaction network, the coupled scheme of coke formation and catalyst deactivation were specified for n-heptane catalytic cracking. The dual-model was proposed for the process simulation of n-heptane catalytic cracking over HZSM-5 zeolites. It predicted not only the conversion and product distribution but also coke content with the acceptable errors.

A CFD Model to Evaluate Near-Surface Oil Spill from a Broken Loading Pipe in Shallow Coastal Waters

Oil spills continue to generate various issues and concerns regarding their effect and behavior in the marine environment,owing to the related potential for detrimental environmental,economic and social implications.It is essential to have a solid understanding of the ways in which oil interacts with the water and the coastal ecosystems that are located nearby.This study proposes a simplified model for predicting the plume-like transport behavior of heavy Bunker C fuel oil discharging downward from an acutely-angled broken pipeline located on the water surface.The results show that the spill overall profile is articulated in three major flow areas.The first,is the source field,i.e.,a region near the origin of the initial jet,followed by the intermediate or transport field,namely,the region where the jet oil flow transitions into an underwater oil plume flow and starts to move horizontally,and finally,the far-field,where the oil re-surface and spreads onto the shore at a significant distance from the spill site.The behavior of the oil in the intermediate field is investigated using a simplified injection-type oil spill model capable of mimicking the undersea trapping and lateral migration of an oil plume originating from a negatively buoyant jet spill.A rectangular domain with proper boundary conditions is used to implement the model.The Projection approach is used to discretize a modified version of the Navier-Stokes equations in two dimensions.A benchmark fluid flow issue is used to verify the model and the results indicate a reasonable relationship between specific gravity and depth as well as agreement with the aerial data and a vertical temperature profile plot.

Severity Risk Analysis Matrix Ranking (SRAMR) for Oil-Spill Contingency Planning: Asemoku-Agip Pipeline in Perspective

One of the down sides of crude oil exploration and exploitation in the developing nations is its impacts on the environment. A major manifestation of poor crude oil management is oil-spillages. Mitigation strategies have been too expensive, but a cheaper recent way of managing crude-spills is by developing a severity risk analysis matrix ranking (SRAMR). The spatial data-sets deployed in this study were acquired from the USGS, Google Earth Pro, and NOSDRA. A buffer zone of 100 - 400 meters was created to characterize the LULC characteristics of the area. Also, this was to help develop a risk sensitivity characteristic. The study found that the vegetal cover was the environmental resource at high risk to crude-spills in the area, while other land-uses were at low risk of crude-spill. It is hoped that the finding from this study informs policy development and planning for crude oil spill incidents.

利用n-heptane详细模型对水乳化柴油燃烧的化学动力学研究

以4100QBZL-2型直喷柴油机为模拟对象,采用化学动力学计算软件CHEMKIN与LLNL的n-heptane详细氧化模型为基础,对柴油机燃用纯柴油,10%、20%、30%的水乳化柴油进行化学动力学模拟。数值模拟结果表明:水乳化柴油带来的滞燃期延长、着火滞后等现象,是乳化燃料中的水分在缸内的物理现象引起的。从纯化学动力学方面来看,掺入一定的水分可以促进H、O、OH、HO2等自由基在低温燃烧(LTC)阶段的生成,使得着火提前。通过敏感性分析可知,掺入的水分会对n-heptane氧LTC时期过氧烷基的异构化过程及过氧化氢酮的分解都会产生促进作用,从而导致n-heptane的快速分解及氧化。

A Promising MoO_x-based Catalyst for n-Heptane Isomerization

The SiO2 and g-Al2O3 supported MoOx catalyst and a MoOx-SiO2 catalyst have been studied in a conventional fixed-bed flow reactor for n-alkanes isomerization. It is shown that the MoOx-SiO2 catalyst with SiO2 framework, in which the bulk MoOx phase is large enough to form typical mesoporous structure, is promising in terms of its advantages of both improved mechanical strength and high catalytic properties over the supported MoOx and bulk MoOx catalyst.

Effect of iridium loading on HZSM-5 for isomerization of n-heptane

The effect of iridium loading on the properties and catalytic isomerization of n-heptane over Ir-HZSM-5 is studied. Ir-HZSM-5 was prepared by impregnation method and subjected to isomerization process in the presence of flowing hydrogen gas. XRD and BET studies show that the presence of iridium stabilizes the crystalline structure of HZSM-5, leading to more ordered framework structure and larger surface area. TGA and FTIR results substantiate that iridium species interacts with OH group on the surface of HZSM-5. Pyridine FT-IR study verifies the interaction between iridium and surface OH group slightly increased the Bro¨nsted and Lewis acid sites without changing the lattice structure of HZSM-5. The presence of iridium and the increase of strong Lewis acid sites on HZSM-5 were found to bring an increase about 4.1%, 33.2% and 11.8% in conversion, selectivity and yield of n-heptane isomerization, respectively.

An asymmetric membrane of polyimide 6FDA-BDAF and its pervaporation desulfurization for n-heptane/thiophene mixtures

Polyimide（PI） is a type of important membrane material. A soluble polymer was synthesized from 4,4′-（hexafluoroisopropylidene） diphthalic anhydride（6FDA） and 2,2-bis[4-（4-aminophenoxy） phenyl] hexafluoropropane（BDAF） by the two-step polymerization method. The polymer was proved to be polyimide 6FDA-BDAF by the Fourier transform infrared（FT-IR）, the 1H-NMR and ^（19）F-NMR spectra. An asymmetric membrane was prepared with the synthesized polyimide 6FDA-BDAF, it was porous in the 50 μm height bulk and dense in a 3–5 μm height surface. The membrane was used to separate n-heptane/thiophene mixtures by pervaporation with sulfur（S） contents from 50 to 900 μg g^（–1）. The total flux was enlarged from 7.96 to 37.61 kg m^（–2） h^（–1） with temperature increasing from 50 to 90°C. The membrane＇s enrichments factor for thiophene were about 3.13 and dependent on the experimental conditions. The experimental results demonstrated that polyimide 6FDA-BDAF would be a potential membrane material for desulfurization and controlled release of the S-containing fertilizer.

Oil Spill Risk Assessment of Offshore Pipeline in the Bohai Sea Under the Perspective of Ecological Protection

In recent decades,the exploration and development of marine oil and gas resources have increased significantly to meet the increasing energy demand of mankind.The Bohai Sea is a semi-closed continental sea that has a weak water exchange capacity and high ecological fragility.However,at present,more than 200 oil platforms have been built in the Bohai Sea,with more than 270 offshore oil pipelines having a length exceeding 1600 km.The oil spill pollution of offshore platforms has a great impact on the marine environment and ecosystems.Therefore,a comprehensive assessment of its risks is of great practical significance.This paper systematically constructs a comprehensive oil spill risk assessment model that combines the oil spill risk probability model and the ocean hydrodynamic model.This paper uses the Bohai Sea offshore pipeline as an example to assess its oil spill risk.The high-risk-value areas of the Bohai Sea offshore pipeline are mainly distributed at the bottom of Liaodong Bay,the bottom of Bohai Bay,near the Caofeidian area,and the northern part of the Yellow River Estuary.

SOLUBILITIES OF CARBON DIOXIDE IN MIXTURES OF n-DECANE-n-HEXADECANE AND n-HEPTANE-TOLUENE

Solubilities of CO2 in binary mixtures of n-decane-n-hexadecane and n-heptane-toluenewere measured in a glass apparatus by a synthetic method.Henry’s constants at several temperaturesand solvent compositions were reported.While the Henry’s constants of CO2 in mixtures of decaneand hexadecane can be satisfactorily predicted by a simple linear interpolation,prediction of Henry’sconstants for CO2 in mixtures of heptane and toluene requires excess Gibbs energy of the solvent mix-tures.The standard thermodynamic functions of solution（ΔH0,ΔG0,and ΔS0）were reported.

n-Heptane Isomerization over the Shaped Catalyst Pt/WO_(3)- ZrO_(2) and the Role of the Pseudo-Boehmite Binder

The present paper reports new results regarding the addition of pseudo-boehmite as a binder during the synthesis of shaped Pt/WO_(3)-ZrO_(2)-Al_(2)O_(3) (PtWZA) catalysts. Binder shaping can noticeably influence not only the structure and acidity of catalyst and improve its catalytic performance with regard to n-heptane isomerization, but the mechanical strength of the catalyst. A suitable binder content can improve the isomerization activity or selectivity by changing the acidity of PtWZA. The influence of the binder content depends on the WO_(3) content of the catalyst. PtWZA catalysts that contain 5%-15% binder on a dry basis exhibit favorable isomerization performance that depends on WO_(3) content. Suitable catalysts include Pt20WZ5A and Pt30WZ15A, which provide conversions of approximately 80%-90% and a selectivity of 90%. These new findings enrich researcher knowledge of the effect of the binder on the catalyst shaping process and are useful in the production of industrial catalysts.

A Novel MIL-101(Cr)Acidified by Silicotungstic Acid and Its Catalytic Performance for Isomerization of n-Heptane

The 0.4%Pt/xSTA-MIL-101(Cr)metal-acid bifunctional catalysts were prepared by impregnation using STA-MIL-101(Cr)as the support.The synthesized samples were verified to exhibit a typical octahedral structure of MIL-101(Cr)and the pore structure was arranged orderly.The specific surface area of the samples was extremely high and the samples were made of micro-mesoporous composite materials.Silicotungstic acid could retain its Keggin structure in the 0.4%Pt/xSTA-MIL-101(Cr)samples and the catalyst possessed moderately strong Brønsted acid sites.Besides,the dispersion of Pt particles in MIL-101(Cr)was relatively high.n-Heptane isomerization was first used as a probe to test the novel 0.4%Pt/xSTA-MIL-10(Cr)catalyst.Compared with the conventional silicate catalysts,the catalytic performance of 0.4%Pt/30%STA-MIL-101(Cr)was significantly improved with a n-heptane conversion of 58.93%and an iso-heptane selectivity of 95.68%,respectively,under conditions covering a reaction time of 2 h and a reaction temperature of 260°C.The catalyst could still maintain a relatively high catalytic performance after a reaction time of 5 h.Compared with the non-noble metal catalyst,the catalytic efficiency of 0.4%Pt/30%STA-MIL-101(Cr)is relatively high.The mechanism model of n-heptane isomerization over 0.4%Pt/xSTA-MIL-101(Cr)catalyst was established.

Transport and behavior of marine oil spill containing polycyclic aromatic hydrocarbons in mesocosm experiments

Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs in marine environment after an oil-spill incident.However,interaction between petroleum PAHs and microbial communities in a marine environment remains unclear.Therefore,a series of mesocosm experiments were conducted.in which water-accommodated fraction(WAF)of oil was generated to simulate an oil-spill scenario and to analyze the transport and behavior of marine oil spill containing PAHs with and without dispersants.Results indicate that the application of dispersant could increase the concentration of total PAHs in water column due mainly to significant increase in the concentration of highmolecular weight(HMW)PAHs at a lower removal rate.At the end of the 7-day experiment,significant amount of HMW PAHs were accumulated in sediment.In general,the application of dispersant did not increase the sediment uptake of PAHs but increased the PAHs concentration in water column.

INTERACTION OF PLASMA-LIQUID IN AN OXYGEN GLOW DISCHARGE Ⅰ. OXIDATION OF n-HEPTANE

The plasma liquid phase oxidation of n-heptane was investigated. The selectivity of product formation is far superior to plasma oxidation in the gas phase.

Numerical study of n-heptane/benzene separation by thermal diffusion column

In this article,numerical simulations are performed to investigate the performance of the thermal diffusion column for the separation of n-heptane/benzene mixture.The present work tried to optimize column by analyzing significant parameters such as feed flow rate,temperature and cut.In order to obtain the hydrodynamic and temperature and mass distribution inside thermal diffusion column,computational fluid dynamic(CFD) method is applied to solve the Navier-Stocks equations.Numerical simulations are conducted to study the main parameters in both stationary and time-dependent conditions.By using the separation work unit as a function of cut,the optimal cut for maximum SWU occurs within a limited range of 0.47-0.5 for feed rate between 0.5 and 4 g min^-1.Our findings reveal that the optimum feed rate in the range of optimum cut is about 1 g min^-1.In transient study,results show that the best cut for reaching to steady-state condition is θ=0.5.

Preparation and Property of Ni/TiO₂-SAPO-11 Catalyst for N-Heptane Isomerization

For enhancing the activity of Ni/TiO2-SAPO-11 catalyst, SAPO-11, the precursor was prepared by hydrothermal crystallization, and TiO2-SAPO-11 complex carrier was prepared by sol-gel method, then Ni/TiO2-SAPO-11 was produced by the final product. The catalytic performance of Ni/TiO2-SAPO-11 was studied in n-heptane isomerization, and the impact of catalyst preparation conditions on n-heptane isomerization was discussed in detail. The results showed that, with 20% of TiO2 composition, 2% of Ni capacity percentage and calcined temperature at 500°C, conversion of n-heptane and isomerization selectivity was up to 40.94% and 88.97% respectively.

Parameterization Method of Wind Drift Factor Based on Deep Learning in the Oil Spill Model

Oil spill prediction is critical for reducing the detrimental impact of oil spills on marine ecosystems,and the wind strong-ly influences the performance of oil spill models.However,the wind drift factor is assumed to be constant or parameterized by linear regression and other methods in existing studies,which may limit the accuracy of the oil spill simulation.A parameterization method for wind drift factor(PMOWDF)based on deep learning,which can effectively extract the time-varying characteristics on a regional scale,is proposed in this paper.The method was adopted to forecast the oil spill in the East China Sea.The discrepancies between predicted positions and actual measurement locations of the drifters are obtained using seasonal statistical analysis.Results reveal that PMOWDF can improve the accuracy of oil spill simulation compared with the traditional method.Furthermore,the parameteriza-tion method is validated with satellite observations of the Sanchi oil spill in 2018.

Application of Vegetation Indices for Detection and Monitoring Oil Spills in Ahoada West Local Government Area of Rivers State,Nigeria

The study evaluated the environmental effects of an oil spill in Joinkrama 4 and Akimima Ahoada West LGA,Rivers State,Nigeria,using various vegetation indices.Location data for the spill were obtained from the Nigeria Oil Spill Detection and Response Agency,and Landsat imagery was acquired from the United States Geological Survey.Three soil samples were collected from the affected area,and their analysis included measuring total petroleum hydrocarbons(TPH),total hydrocarbons(THC),and polycyclic aromatic hydrocarbons(PAH).The obtained data were processed with ArcGIS software,utilizing different vegetation indices such as the Normalized Difference Vegetation Index(NDVI),Atmospheric Resistant Vegetation Index(ARVI),Soil Adjusted Vegetation Index(SAVI),Green Short Wave Infrared(GSWIR),and Green Near Infrared(GNIR).Statistical analysis was performed using SPSS and Microsoft Excel.The results consistently indicated a negative impact on the environment resulting from the oil spill.A comparison of spectral reflectance values between the oil spill site and the non-oil spill site showed lower values at the oil spill site across all vegetation indices(NDVI 0.0665-0.2622,ARVI-0.0495-0.1268,SAVI 0.0333-0.1311,GSWIR-0.183-0.0517,GNIR-0.0104--0.1980),indicating damage to vegetation.Additionally,the study examined the correlation between vegetation indices and environmental parameters associated with the oil spill,revealing significant relationships with TPH,THC,and PAH.A t-test with a significance level of p<0.05 indicated significantly higher vegetation index values at the non-oil spill site compared to the oil spill site,suggesting a potential disparity in vegetation health between the two areas.Hence,this study emphasizes the harmful effect of oil spills on vegetation and highlights the importance of utilizing vegetation indices and spectral reflectance analysis to detect and monitor the impact of oil spills on vegetation.

数字物流赋能可持续发展的机制与效应——基于物流碳生产率视角

在社会经济全面数字化和可持续发展背景下,从物流碳生产率视角探究数字物流赋能可持续发展的机制与效应意义重大。基于2015—2020年我国省际面板数据,运用纵横向拉开档次法和CRITIC-G1-Bonferroni算子,分别对各地区数字物流和可持续发展水平进行测算,进而以面板固定效应模型、中介效应模型、门槛模型和空间模型,对数字物流、物流碳生产率与可持续发展之间的逻辑关系进行实证检验。研究发现,数字物流以非线性递增的态势显著促进可持续发展水平的提升,且在东部、东北地区的作用强于中西部地区;其中,物流碳生产率的提高是数字物流释放可持续发展红利的重要机制。同时,数字物流对可持续发展还具有空间溢出效应,表明其对地区间可持续发展水平相互协调、带动也有着不可忽视的积极作用;随着传统产业全面数字化对可持续发展水平的影响不断加深,该溢出效应变得愈加显著,从而带动地区可持续发展水平的均衡提升。为了巩固数字物流为可持续发展带来的红利优势,首先要促进社会资本参与物流数字化转型,建设共享的物流平台和基础设施,淘汰过剩落后产能,形成开放统一的物流市场,并通过设立管理部门制定并监督低碳环保标准。此外,应通过财政支持和税收优惠加强中西部基础设施建设,同时建立地区合作机制,共享资源和技术,优化物流网络,促进区域间协调发展。