Effect of the AL-MCM-41 catalyst on the catalytic pyrolysis of atmospheric petroleum residue (ATR)

Thermogravimetry (TG) was used in this study to evaluate thermal and catalytic pyrolysis of Atmospheric Petroleum Residue (ATR) which can be found in the state of Rio Grande do Norte/Brazil, after a process of atmospheric distillation of petroleum. The utilized sample in the process of catalytic pyrolysis was Al-MCM-41, a mesoporous material. The procedures for obtaining the thermogravimetric curves were performed in a thermobalance with heating rates of 5, 10, and 20 °C min⁻¹. From TG, the activation energy was determined using the Flynn–Wall kinetic method, which decreased from 161 kJ mol⁻¹, for the pure ATR, to 71 kJ mol⁻¹, in the presence of the Al-MCM-41, showing the efficiency of the catalyst in the pyrolysis of Atmospheric Petroleum Residue.     

12-钨磷酸在AlSBA-15上的固定化及其乙酰化催化活性

12-Tungstophosphoric heteropoly acid(TPA) with a Keggin structure was introduced into Al-incorporated mesoporous molecular sieves(AlSBA-15) by the incipient wetness method.The materials were characterized by X-ray diffraction,nitrogen adsorption,scanning electron microscopy,UV-Vis diffuse reflectance and Raman spectroscopy,which confirmed the Keggin and mesopore structure.Its catalytic activity was evaluated under solvent-free conditions in the liquid phase at 333-383 K for the propionylation of anisole with propionic anhydride.The catalysts used were AlSBA-15,10%,20%,and 40% TPA/AlSBA-15,and 20% TPA/MCM-48.In the propionylation of anisole with propionic anhydride,the substitution occurred predominantly at the para position.The 20% TPA/AlSBA-15 catalyst gave a total product yield of 48% with 98% selectivity towards 4-methoxypropiophenone.The regenerability of the catalyst was also studied and was found to be excellent.     

Direct synthesis and catalytic evaluation of AlSBA-1

The direct synthesis of the new mesoporous molecular sieve AlSBA-1 containing exclusively tetrahedrally coordinated aluminium and the catalytic activity of the novel material in the isomerization of n-decane are reported.     

Kinetic Parameters of Polyethylene Degradation by the Natural Zeolite Chabazite

High-density polyethylene (PE) was subjected to thermal degradation alone and in the presence of an ammonium-exchanged zeolite chabazite (CHA/PE). The processes were carried out in a reactor connected online to a gas chromatograph/mass spectrometer in order to analyse the evolved products. Polymer degradation was also evaluated by thermogravimetry, from room temperature up to 800°C, under a dynamic nitrogen atmosphere, with multiple heating rates. From the TG curves, the activation energy relating to the degradation process was calculated by using the Flynn and Wall multiple heating rate kinetic model for pure PE and for CHA/PE. The exchanged chabazite exhibited good selectivity for the catalytic degradation of PE to low molecular mass hydrocarbons. This revised version was published online in August 2006 with corrections to the Cover Date.     

Improved thermogravimetric system for processing of oil sludge using HY zeolite catalyst

The oil sludge residue presents an aggregate of hydrocarbons, organic and inorganic impurities, and water. The microporous and mesoporous zeolites are considered promising catalysts for processing of petroleum residues generated in refining processes. The aim of this work was to study the degradation of petroleum sludge obtained from primary processing, with applications of an improved thermogravimetry system and HY zeolite, at specific temperature ranges and degradation times, in order to obtain light gases and distillate fuels. The NaY zeolite was synthesized under hydrothermal treatment of a gel containing sodium silicate, sodium aluminate, and water. The obtained solid material was filtered, dried and calcined, and then ion-exchanged with ammonium chloride and calcined in order to obtain its protonic acid form (HY). The samples’ characterization by TG/DTG, XRD, and SEM proved that the crystalline structure of the faujasite zeolite was obtained. The thermal and catalytic degradation of the petroleum sludge was performed with 1.0 g of sample containing 10% of HY zeolite in the temperatures of 100, 200, 300, 400, and 500 °C, varying the time from 0 to 60 min to each temperature, using an oven with temperature program system, adapted with a Shimadzu precision balance. The curves obtained with this system evidenced that the presence of HY zeolite improves the degradation of the residue, with decreasing of the activation energy for the processes, as determined using the Arrhenius model.

     

Catalytic degradation of polyolefins over hexagonal mesoporous silica: Effect of aluminum addition

Degradations of polypropylene (PP) and polyethylene (PE) over pure hexagonal mesoporous silica and aluminum-containing hexagonal mesoporous silica catalysts were studied in a fixed bed catalytic reactor at 380 and 430 °C, respectively. The thermal and catalytic degradations of both PP and PE in liquid-phase-contact and vapor-phase-contact modes over pure hexagonal mesoporous silica had no significant effect on the product yields. The liquid products were widely distributed in hydrocarbons with boiling point ranges of 36–405 °C. By adding a small amount of aluminum to the hexagonal mesoporous material, aluminium-containing hexagonal mesoporous silica exhibited good performance in cracking heavy molecular weight hydrocarbons into light hydrocarbons. High liquid yields and less coke deposits were obtained in liquid-phase-contact reaction with increasing aluminum content. The liquid products were mainly composed of C₅–C₁₀ hydrocarbons with boiling points of 36–174 °C, and propene, butene, and butane were main components in gaseous products. The effect of degradation temperature was not observed on product yields though degradation rate of polyolefin into liquid products was faster. Conversely, in vapor-phase-contact reaction, an increase in gaseous yield was observed when increasing the amount of aluminum and temperature of the cracking reactor, while the residue yield remained constant.     

Kinetic Parameters of Polymer Degradation by SAPO-37

High density poly(ethylene) has been submitted to thermal degradation alone, and in the presence of silicoaluminophosphate SAPO-37. The processes were carried out in a reactor connected on line to a gas chromatograph/mass spectrometer in order to analyze the evolved products. Polymer degradation was also evaluated by thermogravimetry, from room temperature until 800°C, under nitrogen dynamic atmosphere, with multiple heating rates. From TG curves, the activation energy related to degradation process was calculated using the Flynn and Wall multiple heating rate kinetic model for pure polymer (PE) and for polymer in the presence of catalyst (PE/S37). SAPO-37 showed good selectivity for low molecular mass hydrocarbons in PE catalytic degradation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of the catalyst MCM-41 on the kinetic of the thermal decomposition of poly(ethylene terephthalate)

The aim of this work is to determine the activation energy for the thermal decomposition of poly(ethylene terephthalate)—PET, in the presence of a MCM-41 mesoporous catalyst. This material was synthesized by the hydrothermal method, using cetyltrimethylammonium as template. The PET sample has been submitted to thermal degradation alone and in presence of MCM-41 catalyst at a concentration of 25% in mass (MCM-41/PET). The degradation process was evaluated by thermogravimetry, at temperature range from 350 to 500 °C, under nitrogen atmosphere, with heating rates of 5, 10 and 25 °C min^?1. From TG, the activation energy, determined using the Flynn–Wall kinetic method, decreased from 231 kJ mol^?1, for the pure polymer (PET), to 195 kJ mol^?1, in the presence of the material (MCM-41/PET), showing the catalyst efficiency for the polymer decomposition process.     

Thermogravimetry applied for catalytic degradation of atmospheric residue of petroleum on mesoporous catalyst

Journal of Thermal Analysis and Calorimetry - Thermogravimetry was used in order to evaluate thermal and catalytic degradation of atmospheric residue of petroleum (ATR) which is found at Brazilian...     

Fischer-Trospch Synthesis on Ordered Mesoporous Cobalt-Based Catalysts with Compact Multichannel Fixed-Bed Reactor Application: A Review

CO hydrogenation to hydrocarbons through Fischer–Tropsch synthesis (FTS) reaction is one of the promising chemical processes, which can convert alternative feedstocks such as natural gas or biomass into synthetic fuels. The FTS reaction has received many attentions due to a limited petroleum resource with an increased demand for using alternative carbon sources such as stranded gas or shale gas. Some proper synthetic methods of an effective FTS catalyst having a larger active metal surface area and a lower deactivation rate are the most important issues for a long-term operation. Therefore, some ordered mesoporous materials (OMM) have been widely investigated in the field of CO hydrogenation using some heterogeneous catalysts. The present brief review paper summarized the various preparation methods of the ordered mesoporous materials for the possible applications of FTS reaction with a lower deactivation rate and a higher catalytic performance. The applications of the ordered mesoporous cobalt oxides for FTS reaction are briefly introduced and the ways to improve a structural stability even under reductive CO hydrogenation conditions by using efficient pillaring materials as well as by preparing mixed metal oxides. A higher catalytic activity of the ordered mesoporous cobalt oxide was also verified in a multi-channel fixed-bed compact reactor having the intersected interlayers of micro-channel heat exchanger. The thermal stability of ordered mesoporous cobalt-based catalysts was mainly affected by a structural stability which can easily remove the heavy hydrocarbons from the inner surfaces.     

Modified generalized kinetic model and degradation mechanistic pathways for catalytic oxidation of NBS dye in Fenton-like oxidation process

Rice husk was utilized as a silica source for the synthesis of mesoporous silica (MS), which was further used for the surface modification of iron oxide nanoparticles (IO-NPs) to form mesoporous silica-modified iron oxide nanoparticles (MSIO-NPs). IO-NPs and MSIO-NPs were characterized using FT-IR, XRD, X-ray photoelectron spectroscopy, vibrating sample magnetometry, nitrogen adsorption–desorption, TEM and dynamic light scattering analysis. The catalytic activity of MSIO-NPs was tested for degradation and mineralization of Nile blue sulphate dye (NBS) in Fenton-like oxidation process. The degradation efficiency and total organic carbon (TOC) removal of NBS dye onto MSIO-NPs was found to be 92.46 and 66.58%, respectively, after 20 min of reaction time using 5 mM of H₂O₂ concentration. Modified generalized kinetic model was developed for TOC removal of dye degradation onto MSIO-NPs, to account for oxidizable compounds, non-oxidizable compounds, and intermediate organic compounds. The intermediate products formed during degradation of NBS dye were detected by LC–MS experiment and ten fragments were identified based on mass to charge ratio (m/z). The mechanistic pathway for degradation of NBS dye onto MSIO-NPs has been proposed.     

Kinetic study of degradation of heavy oil over MCM-41

Thermogravimetry was applied in order to investigate the catalytic degradation of heavy oil (15.4^oAPI) over silica-based MCM-41 mesoporous molecular sieve. This material was synthesised by the hydrothermal method, using cetyltrimethylammonium bromide as organic template. The physicochemical characterization by nitrogen adsorption, X-ray diffraction, and thermogravimetry, showed that the obtained material presents well-defined structure, with a uniform hexagonal arrangement. The thermal and catalytic degradation of heavy oil was performed by thermogravimetric measurements, in the temperature range from 30 to 900 °C, at heating rates of 5, 10, and 20 °C min⁻¹. By using the model-free kinetics, proposed by Vyazovkin, it was determined that the activation energy to degrade the heavy oil was ca. 128 kJ mol⁻¹, and for degradation of oil in presence of MCM-41, this value decreased to 69 kJ mol⁻¹, indicating the performance of the mesoporores catalyst for the degradation process.     

Simulation of the Radiation-Chemical Formation of Peroxyacetyl Nitrates and Aromatic Nitro Compounds

The feasibility of formation of peroxyacetyl nitrates and aromatic nitro compounds in the electron-beam removal of sulfur oxides and nitrogen oxides from the combustion products of organic fuels was studied. A kinetic model of the process was proposed. According to this model, the concentration of the resulting peroxyacetyl nitrates is comparable to the initial concentration of aliphatic hydrocarbons. The degradation of aromatic molecules is accompanied by nitration; in this case, both of the processes occur at approximately equal rates.     

Adsorption of 2-methylbenzoic acid onto MCM-41 mesoporous material: kinetics and equilibrium studies

Ordered mesoporous molecular sieves are widely studied as alternative materials in areas where sorptive and catalytic applications are required. MCM-41 type mesoporous material was tested as sorbent of 2-methylbenzoic acid (MBA), an aromatic carboxylic acid selected as model molecule for adsorption studies on mesoporous silicas. Adsorption kinetic studies of MBA on MCM-41 type materials were carried out using ethanol solutions at different MBA concentrations. Experimental results followed Langmuir isotherm model showing large adsorption capacity (3.5?g/g). Two kinetic models, the pseudo first- and second-order, were selected to describe the adsorption process and to determine the best model fitting with the experimental data. Kinetic parameters for each kinetic equation were calculated and discussed. It was shown that the MBA adsorption process onto MCM-41 material could be described by the pseudo-second-order equation and that the MCM-41 performs as a suitable adsorbent material.     

Exploring meso-/microporous composite molecular sieves with core-shell structures

A series of core–shell‐structured composite molecular sieves comprising zeolite single crystals (i.e., ZSM‐5) as a core and ordered mesoporous silica as a shell were synthesized by means of a surfactant‐directed sol–gel process in basic medium by using cetyltrimethylammonium bromide (CTAB) as a template and tetraethylorthosilicate (TEOS) as silica precursor. Through this coating method, uniform mesoporous silica shells closely grow around the anisotropic zeolite single crystals, the shell thickness of which can easily be tuned in the range of 15–100 nm by changing the ratio of TEOS/zeolite. The obtained composite molecular sieves have compact meso‐/micropore junctions that form a hierarchical pore structure from ordered mesopore channels (2.4–3.0 nm in diameter) to zeolite micropores (≈0.51 nm). The short‐time kinetic diffusion efficiency of benzene molecules within pristine ZSM‐5 (≈7.88×10^?19 m² s^?1) is almost retainable after covering with 75 nm‐thick mesoporous silica shells (≈7.25×10^?19 m² s^?1), which reflects the greatly opened junctions between closely connected mesopores (shell) and micropores (core). The core–shell composite shows greatly enhanced adsorption capacity (≈1.35 mmol g^?1) for large molecules such as 1,3,5‐triisopropylbenzene relative to that of pristine ZSM‐5 (≈0.4 mmol g^?1) owing to the mesoporous silica shells. When Al species are introduced during the coating process, the core–shell composite molecular sieves demonstrate a graded acidity distribution from weak acidity of mesopores (predominant Lewis acid sites) to accessible strong acidity of zeolite cores (Lewis and Brønsted acid sites). The probe catalytic cracking reaction of n‐dodecane shows the superiority of the unique core–shell structure over pristine ZSM‐5. Insight into the core–shell composite structure with hierarchical pore and graded acidity distribution show great potential for petroleum catalytic processes.     

Novel synthesis of tetrahydro-β-carbolines and tetrahydroisoquinolines via three-component reaction using hexagonally ordered mesoporous AlSBA-15 catalysts

Tryptamine, aryl aldehyde, and benzyl chloride undergo smooth coupling using well-ordered mesoporous AlSBA-15 catalyst with hexagonal porous structure in acetonitrile at 80 °C to furnish tetrahydrocarbolines in good yields with a high selectivity. This reaction also proceeds with homoveratrylamine to give the corresponding tetrahydroisoquinolines. A variety of aryl and heteroaryl aldehydes have also been used for producing tetrahydrocarbolines in high yields. This AlSBA-15-promoted Pictet-Spengler reaction provides a mild alternative to the traditional Brönsted or Lewis acids typically employed for the preparation of tetrahydrocarbolines and tetrahydroisoquinolines.     

Study of degradation kinetics of sunflower oil on H-Beta zeolite

In this study, were studied the degradation of pure sunflower oil and mixed with H-Beta zeolite. This zeolite was synthesized by the hydrothermal method, followed by calcination and ion exchanged. The characterization of the zeolite was performed by X-ray diffraction and nitrogen adsorption/desorption by the method of BET. The analysis showed that H-Beta zeolite presented a good crystallinity and the template was completely removed from the catalyst. The thermal and catalytic degradation study was carried out using the TG/DTG method in multiple heating rates of 5, 10, and 20 °C min⁻¹. The isoconversion method proposed by Vyazovkin was applied to determine the kinetic parameters for degradation of the sunflower oil. The activation energy for the degradation process of pure sunflower oil was 193 kJ mol⁻¹, while for sunflower oil mixed with 20% of H-Beta zeolite was equivalent to 88 kJ mol⁻¹. It was verified that for the degradation of 90% of the sunflower oil mixed with H-Beta, for a period of 1 h, a temperature of 356 °C was required, whereas for the pure vegetable oil, this value was of 387 °C, at the same time period, showing that the catalyst was effective for the degradation process of sunflower oil.     

Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam using mesoporous molecular sieves ALSBA-15

Vapor-phase synthesis of ε-caprolactam (ε-C) from cyclohexanone-oxime (CHO) has been studied at 300-400^oC and atmospheric pressure using AlSBA-15(X) catalysts with different Si/Al mol ratios X in a fixed-bed, integral-flow reactor. The catalysts were characterized with ICP-AES, XRD, TEM, N₂ adsorption, ²⁷Al and ²⁹Si MAS-NMR, FT-IR and TPD of ammonia. A decrease of X value in AlSBA-15(X) diminishes both the BET surface area and the unit cell length but enhances the acid amount. The catalytic activity correlates with the catalyst acidity. AlSBA-15(10) exhibits excellent catalytic performance. This revised version was published online in June 2006 with corrections to the Cover Date.     

等级孔微孔-介孔Fe2O3/ZSM-5中空分子筛催化材料的制备及催化苄基化性能

ZSM-5分子筛具有极其均匀的孔道结构、 良好的形状选择性和催化活性及耐水热稳定性, 是一种高效、 绿色的固体催化剂, 被广泛应用于石油催化裂化、 精细化工和环境保护等领域. 但其单一的微孔结构大大降低了客体分子的流通扩散性, 导致由大分子参与的芳烃烷基化反应受到极大限制. 本文采用NaOH/四丙基氢氧化铵(TPAOH)混合碱处理微孔ZSM-5, 制备了具备高结晶度、 高比表面积的等级孔微孔-介孔ZSM-5中空分子筛材料, 该材料在保持微孔孔道良好水热稳定性和大量活性中心的同时, 还通过介孔的引入进一步促进反应物及产物的扩散, 使间三甲苯苄基化反应的转化率提高了3.8倍. 通过在等级孔微孔-介孔ZSM-5中空材料上负载Fe, 开发出了具有双功能的等级孔微孔-介孔Fe₂O₃/ZSM-5中空催化剂, 该催化剂在苯的苄基化反应中表现出优异的催化性能, 当Fe负载量(质量分数)为6.67%, 反应温度为75 ℃, 反应时间为15 min时, 转化率高达98.3%, 选择性为81.6%, 最终收率达到80.2%.     

Experimental and kinetic study of catalytic cracking of heavy fuel oil over E-CAT/MCM-41 catalyst

The catalytic cracking of heavy fuel oil was investigated over the equilibrium fluid catalytic cracking catalyst (E-Cat) as a base component with the mesoporous MCM-41 as an additive. The catalytic performance of the E-Cat/MCM-41 system was assessed in a fixed-bed MAT unit. The reaction was performed at temperatures of 500, 530, 550 and 600°C and the product distributions in both gaseous and liquid phases were studied. The yields of products including light olefins, liquefied petroleum gas (LPG), gasoline, dry gas, coke and also the conversions obtained over different temperatures were reported and some generalities discussed. The maximum yield of propylene (17.5%) was obtained at 550°C whereas the highest conversion and gasoline yield was gained at 530°C. An eight-lump kinetic model containing 11 kinetic parameters was considered. Those parameters were estimated based on experimental data at specific temperatures by fourth order Runge–Kutta algorithm and the least square method. In addition, Arrhenius equation was used to calculate apparent activation energies. The calculated data of the product yields were in a close agreement with the experimental data.