Utilisation of Non-Edible Source (Pongamia pinnata Seeds Shells) for Producing Methyl Esters as Cleaner Fuel in the Presence of a Novel Heterogeneous Catalyst Synthesized from Waste Eggshells

Waste eggshells were considered for synthesising a precursor (CaO) for a heterogeneous catalyst, further impregnated by alkali caesium oxide (Cs₂O). The following techniques were used to characterise the synthesised catalysts: X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and Temperature Programmed Desorption (CO₂-TPD). The synthesised catalyst revealed its suitability for transesterification to produce biodiesel. The biodiesel production process was optimised, and it showed that the optimal biodiesel yield is 93.59%. The optimal set of process parameters is process temperature 80 °C, process time 90 min, methanol-to-oil molar ratio 8 and catalyst loading 3 wt.%. It has been found that the high basicity of the catalyst tends to give a high biodiesel yield at low methanol-to-oil ratio 8 when the reaction time is also less (90 min). The fuel properties of biodiesel also satisfied the standard limits defined by ASTM and the EN standards. Thus, the synthesised catalyst from waste eggshells is highly active, improved the biodiesel production conditions and PPSS oil is a potential nonedible source.     

Optimization of process conditions for biodiesel production over CaO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/ZrO<Subscript>2</Subscript> catalyst using response surface methodology

CaO–Al₂O₃/ZrO₂ mixed oxide catalyst was prepared using free-solvent method. The catalyst was characterized using X-ray diffraction, BET surface area, acidity index (obtained by titration method), and scanning electron microscopy (SEM). With calcium aluminate and calcium zirconate been successfully formed, the mix exhibited small crystal size, high acidity, and large surface area, pore size, and pore volume, making it a catalyst of choice for biodiesel production. The activity of catalyst was evaluated in the course of esterification of oleic acid as well as transesterification of waste cooking oil (WCO) into biodiesel. Based on a four-variable central composite design (CCD), response surface methodology (RSM) was used to optimize effective variables on oleic acid conversion. The optimum yield of 94.68% was obtained at the following set of optimum conditions: reaction temperature of 120 °C, methanol/oleic acid molar ratio of 15.64, catalyst concentration of 2.94 wt%, and reaction time of 4 h; the result was in excellent agreement with the predicted values. Furthermore, under the optimum conditions, the catalyst succeeded to convert 93.48% of WCO into biodiesel.     

Zn-La复合氧化物催化剂用于甲醇与碳酸乙烯酯酯交换反应的研究

ZnO、La₂O₃和Zn-La复合氧化物催化剂用于甲醇与碳酸乙烯酯反应制备碳酸二甲酯和乙二醇。催化剂采用共沉淀法进行制备,并用BET、XRD、TG-DSC、CO₂-TPD和Hammett滴定等对催化剂进行表征。考察了Zn-La物质的量比、焙烧温度,反应条件（反应温度、反应时间、催化剂用量等）对催化剂活性的影响。结果表明,ZnLa复合氧化物物质的量比为2：1,焙烧温度为500℃时,催化剂表现了较好的催化效果。催化剂的活性与催化剂表面的碱性强度和碱量有关,碱量越多催化剂的活性越好。     

Synthesis of biodiesel over ZnO/Ca(OH)2/KF catalyst prepared by the grinding method

A novel ZnO/Ca(OH)₂/KF solid base catalyst was prepared by the grinding method and applied to biodiesel synthesis by the transesterification of soybean oil. The effect of various parameters such as KF molar amount, calcination temperature, the amount of catalyst, molar ratio of methanol to oil, reaction temperature, and time on the activity of the catalyst were investigated. The catalysts were characterized by several techniques of thermogravimetry/derivative thermogravimetry, X–ray diffraction, Hammett indicator method, and scanning electron microscopy. The analysis results indicated that the KF interacted with Ca(OH)₂ and formed KCaF₃ phase before calcination of the catalyst. The formed KCaF₃ crystal phase was the main catalytic active component for the catalyst activity. In addition, the basicity of ZnO/Ca(OH)₂/KF was greatly influenced by the different calcination temperates, and the catalyst activity was correlated closely with the basicity. A desired biodiesel yield of 97.6 % was obtained at catalyst amount of 3 %, methanol/oil of 12:1, and reaction time of 1.5 h at 65 °C.     

以催化裂化废催化剂为原料合成NaY分子筛的研究

针对催化裂化(FCC)废催化剂的回收利用问题,提出了一种废催化剂再利用的方法,即以FCC废催化剂为铝源,合成时只补充部分硅源,采用自制的高效NaY沸石导向剂,水热合成NaY分子筛。同时,以普通的化工原料合成了对比试样Y型分子筛。讨论了不同的FCC废催化剂预处理方式对合成产物性能的影响,发现以经过碱熔活化处理的废催化剂为原料合成的Y分子筛拥有更高的结晶度和纯度。采用X射线衍射、热分析、程序升温脱附法(NH3-TPD)和N₂静态容量吸附法对结晶产物和对比样品的晶体结构,热稳定性、酸性质、比表面积以及孔分布进行了表征。结果显示,以FCC废催化剂为原料完全可以合成出与普通原料性能接近的NaY分子筛。其BET比表面积可以达到615 m²·g^-1,孔体积可达0.38 cm³·g^-1,孔径集中在0.51 nm左右。     

Fe3O4/ZnMg(Al)O magnetic nanoparticles for efficient biodiesel production

Fe₃O₄/ZnMg(Al)O solid base catalyst was prepared by calcining ZnMgAl‐LDHs grown on the surface of magnetic Fe₃O₄ synthesized by chemical coprecipitation. The magnetic property of the catalyst was studied by vibrating sample magnetometer. The results showed that the catalyst possessed excellent magnetic responsivity, and it could be recovered by external magnetic field. The magnetic catalyst was also characterized by ICP, TG‐DTG, XRD, SEM, EDS, TEM and N₂ absorption‐desorption. It was found that the catalyst showed a unique porous structure. The reaction conditions affecting biodiesel yield were investigated, the biodiesel yield reached 94% was obtained under the optimal conditions. The biodiesel yield was still above 82% after 7 times of regeneration, and the catalyst can be easily separated and recycled.     

助剂对NiMgAl催化剂的结构和甲烷二氧化碳重整反应性能的影响(英文)

向担载镍基催化剂NiMgAl中添加助剂(Co,Ir或Pt)制备了三种助剂促进型催化剂,通过氢气程序升温还原(H2-TPR),CO2/CH4程序升温表面反应(CO2/CH4-TPSR)和CO2程序升温脱附(CO2-TPD)等方法对催化剂进行表征.助剂对催化剂性能的影响通过甲烷干重整实验进行评价.添加少量的Pt或Ir助剂可以降低Ni活性组分的还原温度和提高反应性能.添加助剂的样品与原始NiMgAl催化剂相比能够降低反应的活化能,添加Co或Ir助剂的催化剂与NiMgAl催化剂相比活化能有了明显的降低.NiMgAl催化剂的活化能为51.8 kJ·mol-1,添加Pt助剂的NiPtMgAl催化剂活化能降至26.4 kJ·mol-1.NiMgAl催化剂中添加Pt助剂制备的催化剂具有较好的催化活性和较低的活化能.CH4-TPSR和CO2-TPSR结果表明添加Pt助剂可以在更低的温度下(与NiMgAl催化剂相比)提高CH4的活化能力,并在催化剂表面形成更多的碳物种.CO2-TPD结果显示,添加助剂的催化剂与NiMgAl样品相比在反应温度区间内增加了CO2的吸附/脱附量.     

Heterogeneous synthesis of glycerol carbonate from glycerol and dimethyl carbonate catalyzed by LiCl/CaO

In this article, a CaO-based catalyst was prepared by impregnating chloride salts on CaO to develop a highly efficient heterogeneous catalyst for the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate. LiCl/CaO exhibited a high catalytic activity under moderate reaction conditions. The effects of the LiCl loadings, the amount of catalyst and the calcination temperature on the catalytic activity were investigated. The highest yield of 94.19% glycerol carbonate was obtained at 65 °C on CaO loaded with 10% LiCl after 1 h, and the catalyst had high stability in reusing work. Scanning electron microscopy (SEM), X-ray diffraction (XRD), BET, CO₂-TPD, XPS and thermalgravity (TG) were used to characterize the prepared catalyst. It was found that the high catalytic activity of CaO after modification with LiCl is associated with the structural aspects and the amount of basicity of the catalyst. The Li₂O₂ species, which is a strong basic site that is formed by the substitution of the Ca²⁺ in CaO lattice by Li⁺, has great activity for transesterification.     

Ce助剂对V/SiO2催化CO2氧化乙苯脱氢性能的影响

通过N₂吸附、X射线衍射(XRD)、X射线光电子能谱(XPS)、H₂程序升温还原(H₂-TPR)、CO₂程序升温脱附(CO₂-TPD)和热重分析(TGA)等多种表征手段和催化反应性能评价,研究了铈助剂的添加对V/SiO₂催化CO₂氧化乙苯脱氢性能的影响. 结果表明,Ce助剂不仅提高了催化剂活性组分分散性和氧化还原性能,抑制了钒物种的深度还原,而且增强了催化剂碱性和CO₂吸附能力,减缓了积炭生成,从而显著提高了V-Ce/SiO₂对CO₂氧化乙苯脱氢反应的催化活性和稳定性. 在本实验中,V(0.8)-Ce(0.25)/SiO₂催化剂表现出最佳的催化性能,苯乙烯(ST)收率可达55.6%,选择性为98.5%,反应12 h 后,催化剂活性基本不变,与惰性N₂气氛比较,CO₂明显促进了乙苯脱氢反应,归因于CO₂能保持催化剂表面钒物种的高价态.     

No-Glycerol rapid heterogeneous biodiesel production on K<Subscript>2</Subscript>CO<Subscript>3</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst by coupling process

Biodiesel containing almost no glycerol has been produced by coupling reaction carried out over K₂CO₃ supported by calcium oxide as solid base catalysts. The solid base catalysts synthesized by wet impregnation exhibit an exceedingly high activity in biodiesel production. It was found that the reaction time required for the highest yield of biodiesel, 99.2%, can be shortened to 30 min over K₂CO₃/Al₂O₃ under the optimum reaction conditions: 8: 1: 1 molar ratio of methanol/DMC/oil, 30 wt % K₂CO₃/Al₂O₃ catalyst, and 65°C reaction temperature. Solid basic catalysts examined in the study were characterized by BET surface area, XRD, CO₂-TPD, and SEM techniques. The strong interaction between K₂CO₃ and the support yields a new basic active site, which can be probably responsible for the high activity of K₂CO₃/Al₂O₃.     

甲烷氧化偶联La－Me－O（Me＝Mg，Ca，Sr，Ba）系催化剂表面氧种的研究

利用ＣＯ_２－ＴＰＤ法考察了Ｌａ－Ｍｅ－Ｏ（Ｍｅ＝Ｍｇ，Ｃａ，Ｓｒ，Ｂａ）系催化剂的表面碱性，并用Ｏ_２－ＴＰＤ、ＣＨ_４－ＴＰＤ法对该体系的表面活性氧种进行了表征，并与催化性能相关联。结果表明，Ｌａ－Ｂａ－Ｏ催化剂由于表面强碱性中心数目多，产生活性氧种的数目也多，有利于甲烷的活化，因而具有最高的甲烷转化率和Ｃ_２烃选择性。脉冲反应表明，在无气相氧存在下，表面晶格氧参与了氧化偶联，而且是选择氧化的活性氧种。     

FeMn、FeMnNa和FeMnK催化剂上合成气制低碳烯烃的比较

研究了钠、钾助剂对FeMn 合成低碳烯烃催化剂结构及性能的影响. 低温N₂吸附、X射线光电子能谱（XPS）、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、CO/CO₂程序升温脱附（CO/CO₂-TPD）、Mössbauer 谱和CO+H₂反应的研究结果表明,增加Mn助剂含量促进了活性相的分散和低碳烯烃的生成,而过多锰助剂在催化剂表面的富集则降低了费托合成反应的CO转化率;钾助剂和钠助剂的加入均抑制了催化剂的还原并且促进了CO₂和CO的吸附. 比较还原后（H₂/CO摩尔比为20）和反应后（H₂/CO摩尔比为3.5）催化剂的体相结构可以发现,在FeMn、FeMnNa和FeMnK催化剂中,由于钾助剂的碱性和CO吸附能力较强,因此体相中FeC_x的含量相对较高;而活性测试结果表明,FeMnNa催化剂拥有最好的CO转化率（96.2%）和低碳烯烃选择性（30.5%,摩尔分数）.     

Use of ZSM-5 catalyst in deoxygenation of waste cooking oil

This study investigated the potential use of waste cooking oil (WCO) in the production of engine fuels and valuable chemicals via catalytic cracking. WCO was processed in its pure form and in a mixture with hydrotreated vacuum gas oil (HVGO). Catalytic cracking experiments were performed using a microactivity test (MAT) (simulation of the fluid catalytic cracking environment). In cracking over the standard fluid catalytic cracking equilibrium catalyst (FCC-ECAT), the oxygen contained in the feed was consumed in the formation of CO and CO₂, water and into oxygenated organic compounds (phenolics, esters, carboxylic acids, etc.), which were found in the organic phase of the liquid product. In order to remove the unwanted organic oxygenates, the catalytic system based on pure FCC-ECAT was modified by addition of the ZSM-5-based FCC catalyst. By using the mixture containing FCC-ECAT and 10 mass % of FCC-ZSM-5, it was possible to reduce the amount of organic oxygenates to almost the feasible minimum when cracking pure WCO. The effect of the catalyst mixture on cracking the feed mixture of the vacuum gas oil with 10 vol. % of WCO was manifested in the practically zero formation of organic oxygenates and in a gasoline yield comparable with vacuum gas oil (VGO) cracking.     

Biomaterials obtained by gelation of silica precursor with CO<Subscript>2</Subscript> saturated water containing a carbonic anhydrase enzyme

As part of an effort to develop biomaterials for the capture of CO₂ catalyzed by a carbonic anhydrase enzyme, the effects of an aqueous CO₂ saturated solution and a carbonic anhydrase on the gelation and texture of SiO₂ gels derived from tetramethoxysilane (TMOS), were studied. Both aqueous CO₂ and the enzyme were found to accelerate the gelation of silica, with a stronger effect when both the enzyme and CO₂ saturated aqueous water, were used. According to the gel texture data, aqueous CO₂ acted as an acid type catalyst, while the carbonic anhydrase acted as a weak base type catalyst. Moreover, a gel with a more granular visual aspect was obtained when both the enzyme and CO₂ saturated water were used. The latter characteristic was consistent with a double action of the enzyme, first as a gelation catalyst on the silica precursor, secondly as a reverse protonation catalyst which accelerated the back nucleation of CO₂ gas bubbles from aqueous HCO₃ ⁻ anions.     

Optimization of biodiesel production via transesterification of soybean oil using α-MoO3 catalyst obtained by the combustion method

A catalyst based on MoO₃ was synthesized by a simple and fast pilot-scale combustion reaction method and applied to the conversion of soybean oil to biodiesel via transesterification. For that, the statistical analysis of the catalyst amount and temperature, factors that influence the process, was evaluated by means of central composite design 2². MoO₃ was characterized in terms of structure by X-ray diffraction (XRD), textural characterization Brunauer-Emmett-Teller (BET), density by helium pycnometry (DE), particle size analysis (DG) and acidity tests by temperature-programmed desorption of ammonia (NH₃-TPD), chemical analysis by X-ray fluorescence (EDX), morphology by scanning electron microscopy (SEM) and catalytic properties. The transesterification products were characterized by gas chromatography (GC), acidity index (AI) and kinematic viscosity (KV). The results indicate the catalyst formation with a surface area of 1.36 m²g^?1, and density of 4.5 g/cm³ which consists of a single crystalline phase of orthorhombic configuration, with total NH₃ acidity of 33.61 μ.mol/g. Morphological characterization revealed that the catalyst is formed by irregular plates of various sizes and shapes, with a wide sizes range of agglomerated particles. In the soybean oil transesterification reactions, the catalyst was active showing 96.9% conversion to ethyl esters. The experimental design was meaningful and predictive, with a reliability level of 95%. The statistical analysis identified temperature as a significant variable for the adopted planning. To conclude, a new single-phase catalyst (α-MoO₃) has been developed and successfully applied to the biodiesel Synthesis from soybean oil. These results have a positive and promising impact for biodiesel production by transesterification of soybean oil against ethanol.     

制备方法对Fe2O3/Al2O3-ZrO2在乙苯脱氢反应中催化性能的影响

为提高含铁催化剂的脱氢活性,采用浸渍法和一步沉淀法制备了Fe、Al和Zr含量相同的F4AZ10-imp和F4AZ10-pre催化剂,在550 ℃考察了其在乙苯CO₂氧化脱氢制苯乙烯反应过程中的催化性能,并结合XRD、N₂-吸附、NH₃-TPD、CO₂-TPD和H₂-TPR等表征手段对催化剂进行了分析。结果表明,与浸渍法相比,一步沉淀法制备的催化剂更有利于活性组分Fe₂O₃在催化剂表面的分散及反应物CO₂的转化。     

柠檬酸辅助固相研磨法制备铜基催化剂及在CO_2加氢合成甲醇反应中的性能研究

通过柠檬酸辅助固相研磨法制备铜基催化剂,采用XRD、TPR、TG-DSC、SEM、BET、TEM、XPS、CO_2-TPD等手段对催化剂性能进行表征.结果表明室温固相研磨的前驱体在惰性气体N_2中焙烧使体系中的CuO绝大部分被原位还原成Cu~0,不需外加H_2还原,直接制得了C/I-Cu/ZnO催化剂,催化剂具有中孔.利用高压固定床连续反应装置对催化剂活性进行了评价,结果表明,柠檬酸用量、前驱体焙烧温度、焙烧升温速率等条件对催化剂活性产生影响,当C_6H_8O_7/(Cu+Zn)摩尔比为1.2/1并Cu/Zn摩尔比1/1,前驱体在N_2中以3 K·min~(-1)升温速率于623 K焙烧3 h,制得的C/I-Cu/ZnO催化剂比表面积最大,Cu~0粒径最小,在CO_2加氢合成甲醇反应中表现出最佳的活性,CO_2转化率、甲醇选择性和产率分别达到了28.28%、74.29%和21.01%.与外加H_2还原的C/H-Cu/ZnO催化剂相比,原位还原C/I-Cu/ZnO催化剂比表面积较大,Cu~0的粒径较小,活性较高.     

Synthesis of glycerol carbonate with high surface area ZrO2–KOH catalyst

High surface area ZrO₂–KOH sample was prepared and used the catalyst for the synthesis of glycerol carbonate (GC) from dimethyl carbonate (DMC) and glycerol. The structure properties of ZrO₂–KOH were characterized by XRD, BET, CO₂-TPD, XPS, and ICP-OES. It was found that the strong basicity of ZrO₂–KOH might be attributed to the oxygen vacancies as well as the big surface area. Experiments were developed to evaluate the effects of catalysis loading, proportion of reactants, temperature and reaction time on the conversion of glycerol to GC. The consequences showed that ZrO₂–KOH was a highly efficient basic catalyst for synthesis of GC from glycerol. The catalytic performance of ZrO₂–KOH is much better than that of ZrO₂–KOH–CP, ZrO₂–NH₄OH, and some reported heterogeneous catalysts. And the higher performance of ZrO₂–KOH was ascribed to the strong basicity. 99.43% conversion was obtained in a particular situation of catalyst/glycerol weight ratio of 3 wt%, DMC/glycerol molar ratio of 3:1, reaction temperature of 80 °C, and reaction time of 2 h. The plausible reaction mechanism for the transesterification on the strong basic active sites was discussed.

     

NiCe bimetallic nanoparticles embedded in hexagonal mesoporous silica (HMS) for reverse water gas shift reaction

Reverse water gas shift (RWGS) reaction is a crucial process in CO₂ utilization. Herein, Ni- and NiCe-containing hexagonal mesoporous silica (Ni-HMS and NiCe-HMS) catalysts were synthesized using an in-situ one-pot method and applied for RWGS reaction. At certain reaction temperatures 500-750 °C, Ni-HMS samples displayed a higher selectivity to the preferable CO than that of conventionally impregnated Ni/HMS catalyst. This could be originated from the smaller NiO nanoparticles over Ni-HMS catalyst. NiCe-HMS exhibited higher activity compared to Ni-HMS. The catalysts were characterized by means of TEM, XPS, XRD, H₂-TPR, CO₂-TPD, EPR and N₂ adsorption-desortion technology. It was found that introduction of Ce created high concentration of oxygen vacancies, served as the active site for activating CO₂. Also, this work analyzed the effect of the H₂/CO₂ molar ratio on the best NiCe-HMS. When reaction gas H₂/CO₂ molar ratio was 4 significantly decreased the selectivity to CO at low temperature, but triggered a higher CO₂ conversion which is close to the equilibrium.     

The Strongest Acid: Protonation of Carbon Dioxide

The strongest carborane acid, H(CHB₁₁F₁₁), protonates CO₂ while traditional mixed Lewis/Brønsted superacids do not. The product is deduced from IR spectroscopy and calculation to be the proton disolvate, H(CO₂)₂⁺. The carborane acid H(CHB₁₁F₁₁) is therefore the strongest known acid. The failure of traditional mixed superacids to protonate weak bases such as CO₂ can be traced to a competition between the proton and the Lewis acid for the added base. The high protic acidity promised by large absolute values of the Hammett acidity function (H₀) is not realized in practice because the basicity of an added base is suppressed by Lewis acid/base adduct formation.