H2SO4-catalyzed isobutane alkylation under low temperatures promoted by long-alkyl-chain surfactant additives

To deeply understand the role of surfactants on the acid/C4 hydrocarbon miscibility, the catalytic activity and molecular-level interfacial properties of long-alkyl-chain cationic surfactants (hexadecyltrimethylammonium bromide, CATB and dihexadecyldimethylammoniumchloride, DDAB) and anionic one (sodium dodecyl benzene sulfonate, SDBS) were studied as additives for H₂SO₄ alkylation using experiments and molecular dynamics simulations. Surfactant additives are found to efficiently decrease by-products and promote higher selectivity of trimethylpentanes (TMPs) and higher research octane number (RON), which is attributed to the improvement of acid/hydrocarbons interface, including better interfacial dispersion, higher I/O ratio, and lower interfacial tension. Surfactant additives show an interfacial intensification, quite different from intrinsic reaction intensification by low temperature. Combination of SDBS additive and lower temperature contributes to significantly higher TMP selectivity and higher RON up to 84.20 wt% and 99.07 at 269.2 K from 60.21 wt% and 94.34 at 281.2 K, respectively. The information provides good reference for the industrial H₂SO₄ alkylation.     

Understanding interfacial behaviors of isobutane alkylation with C4 olefin catalyzed by sulfuric acid or ionic liquids

The interfacial properties between the hydrocarbon phase including isobutane and 2‐butene and the catalyst phase including H₂SO₄ or ionic liquids (ILs) with various alkyl chain length on their imidazolium cations have been investigated using molecular dynamics (MD) simulations. Compared to H₂SO₄, ILs can obviously improve the interfacial width, solubility and diffusion of reactants at the interface. The ILs with longer chains on cations exhibit a significant density enrichment of alkyl chains at the interface and tend to orient themselves with alkyl chains perpendicular to the interface and protruding into the reactant phase, which is in good agreement with the van der Waals energy between the reactants and cations of the ILs. The ILs with longer chains can improve the interfacial width and facilitate the dissolution of isobutane in catalyst phase, and thus exhibit a better catalytic performance, which agrees well with alkylation experiments in this work. © 2017 American Institute of Chemical Engineers AIChE J, 64: 950–960, 2018     

Enhanced catalytic performance of H2SO4-catalyzed C4 alkylation by formyl functional [N1,1,1,1][C10SO4] additive

It is of fundamental importance to assess the additive for isobutane alkylation catalyzed by the concentrated H₂SO₄ in actual industrial reactor, which usually contains 6.0–7.0 wt% red oil (ASO) impurity. Herein, the formyl functional [N_1,1,1,1][C₁₀SO₄] additive was developed to enhance the catalytic performance of the H₂SO₄ taken from industrial stream with emphasis on process optimization and reaction kinetics. The ASO that existed in the H₂SO₄ from industrial stream has a promoting effect, and the introduction of [N_1,1,1,1][C₁₀SO₄] with ratio of 0.3 wt% can further improve research octane number of alkylate even in a shorter reaction time. The kinetic model can well predict the concentration changes of key components, in which [N_1,1,1,1][C₁₀SO₄] contributes to the larger reaction rate and lower activation energy for the targeted trimethylpentanes generation due to the intensified isobutane solvation. Hopefully, the novel additive has a promising application to optimize the H₂SO₄-catalyzed industrial alkylation process.     

Promoting the sulfuric acid catalyzed isobutane alkylation by quaternary ammonium ionic liquids

Seven typical quaternary ammonium ionic liquids, amino acid ionic liquids, and imidazolium ionic liquids were synthesized, characterized, and investigated as co-catalyst for the sulfuric acid catalyzed isobutane alkylation. The results show that the introduction of [OPSIm][HSO₄] or [Pr₃NPS][HSO₄] both leads to a better catalytic performance and higher quality of alkylate products. The molecular dynamic simulation indicates that the [OPSIm][HSO₄] can promote the dissolution of isobutane molecules at interface, further improving the ratio of isobutane to olefin from 1.02 to 1.18. Differently, the [Pr₃NPS][HSO₄] can significantly increase the interface width from 0.66 to 0.97 nm and reduce the interface tension from 28.49 to 14.62 mN/m, thereby enhancing the reaction area and improving the ion transfer. The [Pro][HSO₄] and [Gly][HSO₄] result in a worse quality of alkylate products due to no positive effect on the interfacial properties such as interfacial solubility of isobutane.     

Thermodynamic and molecular insights into natural gas dehydration using choline chloride-based deep eutectic solvents

Deep eutectic solvents (DESs) as promising green drying agents were first proposed to natural gas (NG) dehydration. In this work, choline chloride (ChCl)-based DESs were prepared using ChCl as hydrogen bond acceptor (HBA) and triethylene glycol (TEG), ethylene glycol (EG) or Urea as hydrogen bond donors (HBDs). To explore the potential application, methane (CH₄) dehydration experiment was conducted to verify the dehydration performance using prepared DESs. The thermodynamic properties were predicted by COSMO-RS model (Conductor-like screening model for real solvents). The quantum chemistry calculation was applied to understand the separation mechanism at the molecular level. The absorption performance of H₂O in DESs depends on the weak interaction between Cl atom (or N and O atom) of ChCl and H atom of H₂O as well as the free volume of DESs. Molecular dynamics (MD) simulation discloses the intermolecular interaction between HBA and HBD. This work makes the first multi-scale analysis on NG dehydration using DESs.     

离子液体/硫酸催化C4烷基化反应过程强化——表界面特性研究

利用分子动力学（MD）模拟研究了不同支链长度以及官能团的Brønsted酸性离子液体（BILs）对H₂SO₄/C₄烷烯界面特性的调控。结果表明,BILs的加入可以明显增强C₄烷烯在两相界面处的溶解和扩散,有利于烷基化油品的提升。烷基链较长的阳离子表现出较强的界面密度富集现象,并且其支链倾向于伸入C₄烷烯相,有利于界面性质的增强。阳离子支链的增长能够促进C₄烷烯的溶解,同时增大了C₄烷烯的界面存留率,不利于其界面扩散。另外,相比于非磺酸功能化离子液体（non-SFILs）,磺酸功能化离子液体（SFILs）促进了C₄烷烯的溶解,但抑制了C₄烷烯的扩散。本文在C₄烷基化界面性质方面的研究有利于深入理解C₄烷基化过程,相关结果有望为烷基化过程强化和新型催化剂的优化和设计提供帮助。     

SO2 absorption/desorption performance of renewable phenol-based deep eutectic solvents

Six renewable DESs prepared from choline chloride (CC) and phenols (guaiacol, GC; cardanol, CL) with molar ratios of phenols to CC of 3:1, 4:1 and 5:1 were investigated to absorb SO₂ at 293.15–323.15 K and 0–1.0 bar. Results showed that DESs demonstrated satisfactory SO₂ absorption performance, and GC–CC (3:1) exhibited the maximum absorption capacity of 0.528 g SO₂ per g DES. The SO₂ enriched DESs could be easily regenerated and recycled five times. Moreover, the DESs exhibited high selectivity of SO₂/CO₂. Present DESs seem to be promising absorbents for SO₂ due to good performance.     

Acidic protic ionic liquid-based deep eutectic solvents capturing SO2 with low enthalpy changes

With the aim of lowering energy consumption for gas regeneration, rational design of absorbents with low absorption enthalpy changes while retaining good gas solubility is of both scientific and practical significance. Herein, we demonstrated that acidic protic ionic liquid (APIL)-based deep eutectic solvents (DESs), which comprise N-ethylimidazole hydrochloride ([EimH]Cl) and ethylene glycol (EG), were able to reversibly absorb SO₂ with high solubility (11.60 mol kg⁻¹) and SO₂/CO₂ selectivity (655) at 293.2 K and 101.3 kPa. Meanwhile, [EimH]Cl/EG DESs exhibit very low enthalpy changes (Δ_rH_m) ranging from −27.1 to −25.6 kJ mol⁻¹, and thus ease of desorption at very mild temperature conditions (303.2 K) with desorption ratios up to 99.6%. Recycling experiments showed that no obvious loss in capacity was found after six absorption–desorption cycles, suggesting good regeneration performance of [EimH]Cl/EG DESs. Moreover, spectroscopic analysis revealed the charge-transfer interaction between [EimH]Cl/EG and SO₂.     

Optimized properties of ZnO nanorod arrays grown on graphene oxide seed layer by combined chemical and electrochemical approach

Novel hybrid architectures based on ZnO nanostructures supported on reduced graphene oxide films are reported by a facile two-step aqueous electrochemical approach. Graphene oxide (GO) obtained by oxidizing graphite with either H₂SO₄:H₃PO₄ mix or H₂SO₄ was subjected to electrochemical reduction (ErGO) by constant potential and sweeping potential methods and further employed as seeding layer for electrodeposition of ZnO nanorods. The results showed the GO reduction rate was markedly influenced by oxygen content while Infrared spectroscopy indicated the sweeping potential was effective in removing the carbonyl and alkoxy groups but also as more defect-inducing reduction approach than constant potential, according to the Raman measurements. The subsequent electroreduction of ErGO during the electrodeposition of ZnO resulted in interfacial interaction between the seed layer and ZnO nanorods. H₂SO₄:H₃PO₄ mix induced a less disrupted graphitic plane in GO which proved beneficial for the growth of higher density ZnO nanorods with improved crystalline quality. By controlling the chemical introduction/electroreduction conditions for oxygen groups in GO materials, the interfacial interaction with ZnO nanorods and their properties could be tailored in order to obtain high performance nanoplatforms.     

Physicochemical properties,surface active species and formation of reverse micelles in the Cyanex 923‐n‐heptane/cerium(IV)‐H2SO4 extraction system

BACKGROUND: The Cyanex^® 923 (trialkylphosphine oxides, TRPO)‐n‐heptane/cerium(IV)‐H₂SO₄ extraction system has been investigated focusing on the physicochemical properties, surface active species and interfacial phenomena. The effects of H₂SO₄ and Ce(IV) extraction on them were considered. RESULTS: Results showed that the density and refractive index reflect the mass transfer by H₂SO₄ and Ce(IV) extraction and the change of refractive index was more sensitive than density. The interfacial tension decreased on extraction of H₂SO₄ but increased on extraction of Ce(IV). The viscosity of the equilibrium organic phase increased abruptly when the extracted H₂SO₄ concentration in the organic phase reached certain high values. The formation of reversed micelles, with mean diameter of about 10 nm, at high H₂SO₄ concentrations in the organic phase, is suggested by various measurements such as viscosity, interfacial tension and dynamic light‐scattering (DLS). CONCLUSION: It is suggested that TRPO‐H₂SO₄ complexes are more surface‐active than TRPO itself and tend to aggregate into reverse micelles by self‐assembling in the organic phase but the Ce(IV)‐TRPO complexes are neutral, less surface‐active than TRPO and not helpful for reverse micelle formation. Copyright © 2008 Society of Chemical Industry     

磺酸功能化离子液体催化甘油与甲醇醚化反应

考察了[HSO₃-bmim]CF₃SO₃、[HSO₃-bmim]P-TSA、[HSO₃-bmim]HSO₄和[HSO₃-bmim]H₂PO₄四种磺酸功能化离子液体对甘油与甲醇醚化反应的影响。结果表明,离子液体的催化性能与其酸强度相关联,[HSO₃-bmim]CF₃SO₃离子液体的酸强度最强,其催化性能也最好。以[HSO₃-bmim]CF₃SO₃为催化剂,在w([HSO₃-bmim]CF₃SO₃)/w(甘油)=0.5:1(质量比)、n(甲醇)/n(甘油)=8:1(摩尔比)、反应温度190℃、反应时间8 h时,甘油的转化率为84.5%,单甲基甘油醚的选择性为41.4%,二甲基甘油醚和三甲基甘油醚的联合选择性为34.1%。在此基础上,提出了离子液体[HSO₃-bmim]CF₃SO₃催化甘油与甲醇醚化反应的反应机理。     

磺酸功能化离子液体催化制生物柴油的性能

通过1-烯丙基咪唑与1,4-丁基磺酸内酯反应制备的两性离子分别与硫酸、三氟甲基磺酸、磷钨酸、磷钼酸和硅钨酸直接反应制备了5种磺酸功能化离子液体。采用¹H NMR、FTIR、TG/DTA等技术手段对其结构及热稳定性进行了表征。最后通过催化油酸与甲醇酯化反应制生物柴油过程对催化剂的催化活性和重复使用性进行了评价。结果表明,5种离子液体均具有高催化活性（高于浓硫酸）,并且重复使用4次后,催化活性基本保持不变。3种杂多酸离子液体不溶于产物,以固态形式与产物混合,为其回收和重复利用提供了有利条件。     

Ab initio study of the selective alkylation of m-cresol with tert-butanol catalyzed by SO3H-functionalized ionic liquids

Our previous work showed that for catalytic alkylation of m-cresol with tert-butanol (TBA) SO₃H-functionalized ionic liquids exhibited several characteristic advantages over conventional catalysts. This work investigated the reaction mechanism of the alkylation of m-cresol with tert-butanol catalyzed by the SO₃H-functionalized ionic liquid (IL) through quantum chemical calculation in combination with the experimental studies. The experimental results showed that 2-tert-butyl-5-methyl phenol (2-TBC), 4-tert-butyl-3-methyl phenol (4-TBC) and tert-butyl-m-cresol ether (TBMCE) products were all primary products, while 2,6-di-tert-butyl-3-methyl phenol (2,6-DTBC) was a secondary product. The calculation results indicated that the selectivities of the products depended on the fundamental natures of the reactive sites, including the orbital overlap, the Coulomb and the steric effect in the interaction between the tert-butyl ion ([t-C₄H₉]⁺) and the m-cresol; the TBMCE was dynamically favored but not thermodynamically stable, while the C-alkylated products, especially 2-TBC, were the thermodynamically preferred products; the IL played an important role in generating the [t-C₄H₉]⁺ from the TBA and the final products from the intermediates.     

Intensification of the Sulfuric Acid Alkylation Process with Trifluoroacetic Acid

H₂SO₄ alkylation of isobutane and butene is one of the primary commercial processes used to produce alkylates. This work presents a technology for the intensification of sulfuric acid alkylation with the addition of trifluoroacetic acid (TFA). The addition of TFA increased the solubility of isobutane in H₂SO₄, decreased its viscosity, and adjusted the acidity of H₂SO₄. With the addition of TFA, the selectivity of C8 was dramatically improved from 36.8 to 95.7%. The TFA content, stirring speed, reaction temperature, volume ratio of acid to hydrocarbon (H/C), molar ratio of isobutane to 2-butene (I/O), reaction time, and reuse of H₂SO₄/TFA were also investigated in this work. Compared with the conventional process, the new technology provided a considerably higher quality alkylation with considerably lower energy consumption. © 2018 American Institute of Chemical Engineers AIChE J, 65: 113–119, 2019     

Reactive compatibilization of LLDPE/PS blends with a new type of Lewis acid as catalyst

The reactive compatibilization of LLDPE/PS (50/50 wt%) was achieved by Friedel–Crafts alkylation reaction with a combined Lewis acids (Me₃SiCl and InCl₃·4H₂O) as catalyst. The graft copolymer at the interface was characterized by Fourier transform infrared spectroscopy and the morphology of the blends was analysized by scanning electron microscopy. It was found that the combined Lewis acids had catalytic effect on Friedel–Crafts alkylation reaction between LLDPE and PS, and the catalytic effect was maximal when the molar ratio of InCl₃·4H₂O to Me₃SiCl was 1:5. The graft copolymer LLDPE–g–PS was formed via the F–C reaction and worked as a tailor-made compatibilizer to reduce the interfacial tension. The mechanical properties of reactive blend with combined Lewis acids as catalyst was notably improved compared to that of physical LLDPE/PS blend and serious degradation had been decreased compared to the reactive blend system with AlCl₃ as catalyst; we interpreted the above results in term of acidity of combined Lewis acids.     

Zirconium incorporated micro/mesoporous silica solid acid catalysts for alkylation of <Emphasis Type="Italic">o</Emphasis>-xylene with styrene

The design of micro/mesoporous silica materials with solid acid catalysts for the catalytic reactions can inject new vitality into the development of nanostructures. In this paper, zirconium was successfully incorporated into micro/mesoporous silica by the direct hydrothermal synthesis, employing P123 and protic ionic liquid as the structure-directing agent. The physico-chemical properties of the micro/mesoporous silica-zirconia were characterized by means of X-ray scattering, N₂ gas sorption, scanning electron microscopy, transmission electron microscopy and NH₃ desorbed TPD methods. The influence of Si/Zr ratio and different calcination temperature on the acidity and catalytic properties were discussed. Also, the catalytic activities of solid acid catalysts were evaluated by the alkylation of o-xylene with styrene. The results indicate that the heteroatom of zirconium has been successfully incorporated into the structure framework and the solid acid catalysts still possess hierarchically porous structure. The prepared catalytic materials contain moderate to strong acid sites, meanwhile, the amount of strong acid sites increases with a decrease of Si/Zr ratio. The SZ-10-SO₄ ^2? (molar ratio of Si/Zr = 10) catalyst was found to be the most promising and gave the highest selectivity among all catalysts, which was due to the strong interaction between H₂SO₄ and micro/mesoporous materials in the presence of Zr, thus prevent H₂SO₄ leaching from the materials. It is worth noting that SZ-10-937 (calcined at 937 K) also has the higher yield of PXE, which maybe the enhancement of crystallization of tetragonal ZrO₂ made the strong acid sites for SZ-973 sample be more than that of the other samples with the increase of calcination temperature.     

Influence of Dopant Ions on the Properties of Conducting Polyacrylamide/Polyaniline Hydrogels

Polyaniline-impregnated polyacrylamide conducting hydrogels have been synthesized chemically via interfacial polymerization route using different acidic doping agents like sulfuric acid (H₂SO₄), hydrochloric acid (HCl), and perchloric acid (HClO₄). The best properties were found in case of H₂SO₄-doped polyacrylamide/polyaniline sample when compared with other doping agents. The resulting hydrogel exhibits superior properties including compact structure, high crystallinity, good mechanical strength, and electrical conductivity. The maximum electrical conductivity of the order of 9.4 × 10^?5 S/cm was found in case of H₂SO₄ doped polyacrylamide/polyaniline.     

Removal of Dibenzothiophene from Diesels by Extraction and Catalytic Oxidation with Acetamide‐Based Deep Eutectic Solvents

A series of acetamide‐based deep eutectic solvents (DESs) with different proportions were prepared. Extraction and catalytic oxidation desulfurization (ECODS) of the acetamide‐based DESs were investigated and the process was optimized. Such DESs with a molar ratio of acetamide and p‐TsOH of 1/3 (C₂H₅NO/3p‐TsOH) exhibits such a remarkable catalytic activity that the dibenzothiophene (DBT) removal could reach 100 % under optimized conditions. C₂H₅NO/3p‐TsOH was used for the oxidative desulfurization of actual commercial diesel. The sulfur removal of diesel achieved up to 98 %. C₂H₅NO/3p‐TsOH could be recycled six times and the desulfurization activity was slightly decreased. Evaluation of the mechanism indicated that oxidative desulfurization (ODS) was realized via dual activation of acetamide‐based DESs. A novel and effective way for deep desulfurization of diesel is provided.     

Modification of dry‐spun Suplon polyimide fibers by mixed‐acid oxidation and their effects on the properties of polypropylene‐resin‐based composites

In this study, the effects of mixed‐acid oxidation on the contents of surface elements, morphology, fiber fineness, mechanical properties, mass change rate, chemical structure, and microaggregate structure of dry‐spun Suplon polyimide (PI) fibers were systematically investigated with wet chemical treatment with HNO₃/H₂SO₄. Experiments investigating both the improvement in the O/C ratio of the fiber surface elements and the changes in other performance features were conducted through the functional modification of the fibers. Meanwhile, the causes of specific changes in the mechanical properties of the oxidized PI‐fiber‐reinforced polypropylene‐resin‐based composites were studied and are discussed. The results of this study demonstrate that the treatment of the fibers with HNO₃/H₂SO₄ mixed‐acid oxidation resulted in significant changes in the properties of the fibers; these changes included an uneven surface, increased specific surface area and surface roughness, a locally etched surface, increased surface energy and O/C ratio, an enhanced wettability, an increased fiber fineness, reduced mechanical properties, and a mass gain in the fibers. Although the chemical structures of the fibers treated by oxidized HNO₃/H₂SO₄ were not significantly changed compared to those of the untreated fibers, the microscopic aggregation of the treated fibers changed to some degree, and the ratio of the amorphous regions significantly increased. Taken together, the functional modification of the PI fiber surface was achieved efficiently through the use of a suitable HNO₃/H₂SO₄ oxidation process and with other performance features of the fibers taken into account. This was favorable for the enhancement of the interfacial properties of the polypropylene fibers and the matrix resins, and thus, the modification improved the mechanical properties of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44932.