Alkylation Process Research Articles

Multi-agent distributed control of integrated process networks using an adaptive community detection approach

This paper focuses on developing an adaptive system decomposition approach for multi-agent distributed model predictive control (DMPC) of integrated process networks. The proposed system decomposition employs a refined spectral community detection method to construct an optimal distributed control framework based on the weighted graph representation of the state space process model. The resulting distributed architecture assigns controlled outputs and manipulated inputs to controller agents and delineates their interactions. The decomposition evolves as the process network undergoes various operating conditions, enabling adjustments in the distributed architecture and DMPC design. This adaptive architecture enhances the closed-loop performance and robustness of DMPC systems. The effectiveness of the multi-agent distributed control approach is investigated for a benchmark benzene alkylation process under two distinct operating conditions characterized by medium and low recycle ratios. Simulation results demonstrate that adaptive decompositions derived through spectral community detection, utilizing weighted graph representations, outperform the commonly employed unweighted hierarchical community detection-based system decompositions in terms of closed-loop performance and computational efficiency.

Synthesis and Performance Evaluation of Metallocene Polyalphaolefins (mPAO) Base Oil with Anti-Friction and Anti-Wear Properties

Anti-wear and anti-oxidation abilities are two key properties of lubricants that play a crucial role in ensuring long-term stable equipment operation. In this study, we aimed to develop a base oil with good anti-oxidation and anti-wear properties for use under extreme pressure. The as-prepared metallocene polyalphaolefin (mPAO) was chemically modified using the trifluoromethanesulfonic acid (TfOH) catalysis through an alkylating reaction with triphenyl phosphorothioate (TPPT). During the experiments, when the reaction temperature exceeded 70 °C or the concentration of TfOH exceeded 2.67%, the β-scission reaction in the alkylation process became significantly more pronounced. The physical and chemical properties of TPPT-modified mPAO (T-mPAO) were evaluated by nuclear magnetic resonance spectroscopy, Fourier trans-form infrared spectroscopy, gel–permeation chromatography, and ASTM standards. T-mPAO showed significantly improved antioxidant capacity, with the initial oxidation temperature increasing by 32 °C compared to the base oil, and it exhibited the slowest increase in acid number in the 96-h oven oxidation test. The tribological tests showed that T-mPAO had the lowest friction coefficient, wear track, and wear rate (72.7% lower than that of mPAO) as well as the highest PB (238 kg) and PD (250 kg) among all tested samples. Compared to mPAO, the average friction coefficient of TPPT-modified mPAO in the four-ball friction test was reduced by 30.5%, and by 16.4% in the TE77 reciprocating friction test. Based on the experimental results, T-mPAO had strong anti-oxidation ability and excellent lubricating performance.The successful synthesis of multifunctional mPAO has enabled lubricant base oil additization, making it possible to use it in more demanding work scenarios, greatly broadening its application scope and making lubricant formulation blending more flexible.

An adaptive distributed architecture for multi-agent state estimation and control of complex process systems

A multi-agent integrated distributed moving horizon estimation (DMHE) and model predictive control (DMPC) framework is developed for complex process networks. This framework utilizes an adaptive spectral community detection-based decomposition approach for a weighted graph representation of the state space model of the system to identify the optimal communities for distributed estimation and control. As the operating conditions of the process network change, the system decomposition adjusts, and the estimation and control agents are reassigned accordingly. These adjustments enable optimizing the integrated DMHE and DMPC architecture, enhancing robustness and closed-loop system performance. The effectiveness of the proposed adaptive distributed multi-agent estimation and control framework is demonstrated through a benchmark benzene alkylation process under various operating conditions. Simulation results show that the proposed multi-agent approach enhances closed-loop performance and computational efficiency compared to traditional system decomposition methods using unweighted hierarchical community detection.

Site-Specific Radical Alkylation of Aryl Cyanide: Visible-Light, Photoredox-Catalyzed, Three-Component Arylalkylation of [1.1.1]Propellane.

We report herein a three-component radical arylalkylation of [1.1.1]propellane toward the synthesis of aryl-substituted bicyclo[1.1.1]pentane derivatives. The use of electron-deficient aryl cyanide as an aryl group source not only reduces the energy barrier of the arylation of the nucleophilic alkyl radical species, but also suppresses the electrophilic Friedel-Crafts alkylation process, enabling the present site-selective arylalkylation.

Research and selection of catalysts for the process of alkylation of oil fractions with catalytic cracking gases

The article presents the results of the study and use of modified zeolite-containing catalysts (ZSM-5) and natural alumosilicates (halloisite) in the process of alkylation of distillate fraction with catalytic cracking gases. Based on thermogravimetric analysis, it was determined that modification of halloisite with the Al+CCl4 system leads to the appearance of peaks indicating exo- and endo processes under the influence of temperature. When the oil fraction was alkylated at a temperature of 50 oC on Al+CCl4+halloisite catalyst with catalytic cracking gases containing olefins of 43.47 % the viscosity index was increased from 32 to 84. Based on NMR spectra, it was determined that alkylates differ from the original oil fraction by increased values isoparaffin index, the number of protons in aromatic structures and those furthes from the aromatic nucleus. These data confirm the improvement in the viscosity temperature characteristics of the oil fraction. Alkylation of an oil fraction with a viscosity index of 49.9 on ZSM-5 and ZSM-5-ZrO2 catalysts made it possible to obtain oils with a viscosity index of 80.7 and 137, respectively. Based on X-ray diffraction studies using rentgenographic method, it was shown that Zr is contained in the structure of ZSM-5 zeolite in the form of ZrO2. The introduction of Zr into the crystaline structure of the zeolite helps to increase the activity of the modified catalyst ZSM-5-ZrO2. Research has shown that the phase composition of samples of the modified ZSM-5-ZrO2 zeolite changes depending on the calcination temperature. An increase in temperature from 200 to 550 oC leads to the transition of the amorphous phase to the crystalline phase, and at a given calcination temperature a phase belonging to ZrO2 appears. The introduction of Zr into the catalyst composition leads to a change in the ratio of the Lewis and Brensted acid sites of the ZSM-5 catalyst. Namely, there is an increased Lewis and a decreased Brensted acid sites. Based on this it can be assumed that both Brensted and Lewis acid sites take part in the alkylation process.

HFIP-Mediated Dual C(Ar)-Alkylation Process Towards the Regioselective Synthesis of Triarylmethanes (TRAMs).

The distinct roles of different chemical species are essential for the discovery of novel chemical transformations in organic synthesis. Here, we have designed a potential strategy for the synthesis of triarylmethanes (TRAMs) using the dual C(aryl)-alkylation process. This protocol was influenced by 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a pivotal reagent and proceeds through the selective para C-H functionalization method. The described approach has been proven to be highly efficient in terms of substrate scope with excellent functional group tolerance and gram scale synthesis of the desired product with 90 % yield. The recyclability and reusability of HFIP has enhanced the feasibility of this protocol towards the sustainable synthesis of TRAMs.

Production of Jet Fuel Range Aromatics by Alkylation of Benzene with Olefins over Bifunctional Ga/ZSM-5 Catalyst.

Aromatic components of C8-C15 are playing indispensable roles in multi-functional properties of jet fuel. Here, we reported the controllable alkylation of benzene with mixed olefins of ethylene and propylene toward C8-C15 aromatic hydrocarbons for jet fuels over the bifunctional Ga/ZSM-5 catalyst. The resultant 2Ga/ZSM-5 exhibited a superior selectivity of 86.4% (yield of 55.5%) to C8-C15 range aromatics, at benzene conversion of 40.3%, ethylene and propylene conversion of 99.5% and 99.2%, respectively. The incorporation of Ga species could effectively weaken the strong acid sites of ZSM-5 and endow 2Ga/ZSM-5 catalyst with appropriate acidity, therefore facilitating the benzene alkylation process and suppressing the undesired hydrogen transfer or aromatization side reactions as well, thus improving the yield of desired C8-C15aromatics for jet fuels. This work provided insight into the development of promising bifunctional catalyst for the oriented transformation of biomass-derived chemicals to aviation fuels.

Photocatalytic Synthesis of γ,γ-Difluoroallylic Ketones and δ,δ-Difluoroallylic Ketones via a Desulfurative/Defluorinative Alkylation Process.

The gem-difluoroalkene moiety is frequently found in medicinal chemistry. From α-keton sulfides and thioic acids, we were able to develop a universal approach for the synthesis of γ,γ-difluoroallylic ketones and δ,δ-difluoroallylic ketones via a desulfurative/defluorinative alkylation process. We expect that this mild and efficient method will be complementary to other known strategies.

Experimental and first-principles investigation on how support morphology determines the performance of the Ziegler-Natta catalyst during ethylene polymerization

One class of the Ziegler–Natta catalysts (ZNC) – the TiCl4/MgCl2 having triethyl aluminum (AlEt3), has been widely utilized during ethylene polymerization. Although the Ti species plays the role of a major active site, an increase of Ti species does not always improve the activity of ZNC. Herein, investigations of experiments and density functional theory (DFT) elucidate this inverse effect of the increased amount of TiCl4 deposition in ZNC because of the pretreatment process. However, the activity of ZNC on pretreated MgCl2 dropped to 60% of the unpretreated one. The DFT demonstrates that the pretreatment strengthened the interaction between TiCl4 and ZNC, especially on the (104) surface, forming the TiCl4-TiCl4 cluster. The existence of this TiCl4-TiCl4 cluster found on the ZNC (104) surface weakens the adsorption of the first AlEt3 molecule and obstructs further alkylation process, making another Ti site of the alkylated TiCl4-TiCl4 cluster inactive. However, the difficult formation of the TiCl4-TiCl4 cluster found on the ZNC (110) is an important key point that enables the activation of all adsorbed TiCl4 on this surface by facilitating the alkylation process. Moreover, the existence of the MgCl2 (110) surface prevents the formation of the TiCl4-TiCl4 cluster significantly. Hence, it is suggested that the existence of the (110) plane on ZNC plays a key role in controlling the performance of the ZNC, especially the stability via the prevention of deactivation caused by the clustering of TiCl4.

Active species in chloroaluminate ionic liquids catalyzing low-temperature polyolefin deconstruction

Chloroaluminate ionic liquids selectively transform (waste) polyolefins into gasoline-range alkanes through tandem cracking-alkylation at temperatures below 100 °C. Further improvement of this process necessitates a deep understanding of the nature of the catalytically active species and the correlated performance in the catalyzing critical reactions for the tandem polyolefin deconstruction with isoalkanes at low temperatures. Here, we address this requirement by determining the nuclearity of the chloroaluminate ions and their interactions with reaction intermediates, combining in situ 27Al magic-angle spinning nuclear magnetic resonance spectroscopy, in situ Raman spectroscopy, Al K-edge X-ray absorption near edge structure spectroscopy, and catalytic activity measurement. Cracking and alkylation are facilitated by carbenium ions initiated by AlCl3-tert-butyl chloride (TBC) adducts, which are formed by the dissociation of Al2Cl7− in the presence of TBC. The carbenium ions activate the alkane polymer strands and advance the alkylation cycle through multiple hydride transfer reactions. In situ 1H NMR and operando infrared spectroscopy demonstrate that the cracking and alkylation processes occur synchronously; alkenes formed during cracking are rapidly incorporated into the carbenium ion-mediated alkylation cycle. The conclusions are further supported by ab initio molecular dynamics simulations coupled with an enhanced sampling method, and model experiments using n-hexadecane as a feed.

Optimization of catalyst service cycle and start-up considering the reactor-distillation-HEN integration and climate

Considering the catalyst deactivation and seasonal temperature variation, a systematic method is proposed for clarifying the dynamic variation of system operating parameters and targeting the optimal catalyst regeneration cycle and start-up date. Relationships between catalyst activity, reactor inlet and outlet temperatures, reactor heat load, and running time are deduced, as well as that between column temperatures, pressures, energy demands, processing capacity, and production month. Diagrams are constructed to illustrate the parameter variations. With the energy consumption and processing capacity combined, an evaluation index is introduced for integrating the reactor-separator-heat exchanger network (HEN) and optimizing the production start-up date. The proposed method is intuitive and efficient and can be used for system design, guiding production, or fault diagnosis. A benzene alkylation process is studied; the optimal regeneration cycle of the ZSM-5 catalyst is 11 months, and the best start-up date is August, saving 2.32 × 105 kgce (kg standard coal) per production cycle.

Continuous alkylation of 1,3,5-trihydroxy-2,4,6-trinitrobenzene in microreactor: Process intensification and reaction kinetics

1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is an essential insensitive energetic material. The alkylation of 1,3,5-trihydroxy-2,4,6-trinitrobenzene (Trinitrophloroglucinol, TNPG), which yields 1,3,5-triethoxy-2,4,6-trinitrobenzene (TETNB), is a pivotal step for the synthesis of TATB. The conventional synthetic process has suffered from long reaction time (∼165 min), intricate procedures, and intensive evaporation of a large number of volatile by-products, which increases the risk of spill and eruption of the reaction system, and necessitates in situ continuous gas–liquid separation. A new process for continuous alkylation in microreactors was proposed in this study. Firstly, a parametric investigation in the batch reactor was performed to explore the effects of various process parameters on the yields, resulting in the optimal experimental conditions, i.e., no reflux condensation, triethyl orthoformate (TEOF) as alkylation reagent, molar ratio of 12, reaction temperature of 120 °C and reaction time of 40 min. Subsequent continuous synthesis in microreactors was conducted, which realized the convenient process operation and no need of gas–liquid separation, leading to substantial improvement in the reaction efficiency and safety. Remarkably, within a packed microreactor, under the reaction temperature of 130 °C and residence time of 3 min, 99.24 % in the yield of TETNB was achieved. Comparing with conventional batch reactors, the required reaction time was reduced to approximately 1/50. Taking the advantages of precise control of temperature and reaction time in the microreactors, the kinetics of alkylation reaction were determined. This innovative approach of continuous synthesis can provide an efficient and alternative route for the synthesis of TATB, as well as other energetic materials and similar processes.

Dehydrative Alkylation of Phenols with Alcohols via Formation of Triflate.

An efficient synergistic trityl cation ([Ph3C][B(C6F5)4])/triflic anhydride (Tf2O) catalyzed alkylation of phenols with alcohols is reported. Benefiting from the formation of the triflate in situ, cheap and readily available active alcohols can be used as the alkylating reagents, and the reaction proceeds under mild reaction conditions with a broad substrate scope. This protocol enables the synthesis of ortho-selective phenols and 2,4,6-trisubstitued phenols containing three different alkyl groups. tert-Amyl triflate was synthesized, and mechanistic studies support a triflate-mediated alkylation process.

Plug Flow Reactor (PFR) Design for the Production of 100,000 tons per year of Cumene from the Catalytic Alkylation of Propylene and Benzene

In a bid to meet the ever-growing global demand for cumene based on its wide range of industrial applications and economic importance, the research considered the design of a plug-flow reactor (PFR) for the production of 100,000 tons of cumene per year from the catalytic alkylation of propylene and benzene. The PFR design models were developed by performing the mass and energy balance over the reactor at steady-state operation. The steady-state PFR performance models were simulated using the MATLAB R2023a version at an initial feed and operating temperature of 481.10 K and 483 K with varying fractional conversions from 0 to 0.95 at 0.05 intervals. At a maximum fractional conversion of 0.95, the PFR design specification for volume, height, diameter, space time, space velocity, quantity of heat generated, and quantity of heat generated per unit volume of the reactor was 19.7707 m3, 4.6523 m, 2.3261 m, 3.8766 s, 0.2580 s-1, 1.8035 J/s, and 0.03448 J/sm3, respectively. The profile behavior of the PFR functional parameters at changes in fractional conversion is in agreement with the trend for PFR operation at steady-state conditions, as shown in Figures 2–10. The evaluation of the PFR yearly production dependent on the reactor volume stood at $2,049.838. The article has shown that PFR is a suitable reaction medium for the catalytic alkylation process for optimum production of cumene and sustainability.

A comprehensive framework for targeting the disturbance propagation path and debottleneck strategy of chemical process considering the topology and cascading effects

For the chemical processes, multiple fluctuations exist, and elucidating the system's dynamic changes is essential in improving its adaptability. With changes in reactor and separator operating conditions and cascading effects related to the system's topological structure considered, a comprehensive framework is established to target the disturbance propagation path and determine cost-effective debottlenecking strategies. Relations among distillation column parameters and the seasonal change in ambient temperature are deduced considering meteorological data, and the utility demand or column pressure under various conditions can be determined. All independent subsystems of the heat exchanger network and their heat surplus/deficit are identified based on the improved information flow diagram and output difference analysis, and the disturbance propagation path is determined. Correlations are deduced to clarify the heat transfer capacity requirement under fluctuating states, and the bottlenecks and cost-effective debottlenecking strategy without topology modification are identified at different stages. The proposed method is intuitive and efficient and can be applied in chemical processes' enhancement, retrofitting, and fault diagnosis. A benzene alkylation process is studied, with the total annual cost decreased by 3.4 %.

A Logarithmic Penalty Function Approach for Enhancing the Alkylation Process in Kaduna and Warri Refineries

A Logarithmic Penalty Function Approach for Enhancing the Alkylation Process in Kaduna and Warri Refineries

Hypercrosslinked polymers with hierarchical pores synthesized using biphenyl crosslinker for carbon dioxide capture

Microporous hypercrosslinked polymers have an upright capacity to develop into prime materials in energy and environmental applications in the near future. The chemical tunability, structural robustness and high surface area are some of the critical factors that lead to their application in the gas adsorption area. Three novel hypercrosslinked porous polymers viz. PABMC, PFBMC and PPzBMC were synthesized via the Friedel-Crafts alkylation process using 4,4′-bis(chloromethyl)biphenyl as the external cross-linker and anhydrous FeCl3 as the catalyst. The polymers obtained are found to be microporous with very high surface areas of 983 m2/g, 1002 m2/g, and 1265 m2/g, respectively, for PABMC, PFBMC and PPzBMC. The polymers PABMC, PFBMC and PPzBMC exhibited appreciable carbon dioxide uptake of 10.18 wt%, 12.02 wt% and 14.18 wt%, respectively, at 273 K. The results reveal a practical approach to synthesizing low-cost heteroatom-rich hypercrosslinked organic polymers with hierarchical pores for gas adsorption and storage applications.

Chloride and Hydride Transfer as Keys to Catalytic Upcycling of Polyethylene into Liquid Alkanes

AbstractTransforming polyolefin waste into liquid alkanes through tandem cracking‐alkylation reactions catalyzed by Lewis‐acid chlorides offers an efficient route for single‐step plastic upcycling. Lewis acids in dichloromethane establish a polar environment that stabilizes carbenium ion intermediates and catalyzes hydride transfer, enabling breaking of polyethylene C−C bonds and forming C−C bonds in alkylation. Here, we show that efficient and selective deconstruction of low‐density polyethylene (LDPE) to liquid alkanes is achieved with anhydrous aluminum chloride (AlCl3) and gallium chloride (GaCl3). Already at 60 °C, complete LDPE conversion was achieved, while maintaining the selectivity for gasoline‐range liquid alkanes over 70 %. AlCl3 showed an exceptional conversion rate of 5000 , surpassing other Lewis acid catalysts by two orders of magnitude. Through kinetic and mechanistic studies, we show that the rates of LDPE conversion do not correlate directly with the intrinsic strength of the Lewis acids or steric constraints that may limit the polymer to access the Lewis acid sites. Instead, the rates for the tandem processes of cracking and alkylation are primarily governed by the rates of initiation of carbenium ions and the subsequent intermolecular hydride transfer. Both jointly control the relative rates of cracking and alkylation, thereby determining the overall conversion and selectivity.

Chloride and Hydride Transfer as Keys to Catalytic Upcycling of Polyethylene into Liquid Alkanes.

Transforming polyolefin waste into liquid alkanes through tandem cracking-alkylation reactions catalyzed by Lewis-acid chlorides offers an efficient route for single-step plastic upcycling. Lewis acids in dichloromethane establish a polar environment that stabilizes carbenium ion intermediates and catalyzes hydride transfer, enabling breaking of polyethylene C-C bonds and forming C-C bonds in alkylation. Here, we show that efficient and selective deconstruction of low-density polyethylene (LDPE) to liquid alkanes is achieved with anhydrous aluminum chloride (AlCl3) and gallium chloride (GaCl3). Already at 60 °C, complete LDPE conversion was achieved, while maintaining the selectivity for gasoline-range liquid alkanes over 70 %. AlCl3 showed an exceptional conversion rate of 5000 , surpassing other Lewis acid catalysts by two orders of magnitude. Through kinetic and mechanistic studies, we show that the rates of LDPE conversion do not correlate directly with the intrinsic strength of the Lewis acids or steric constraints that may limit the polymer to access the Lewis acid sites. Instead, the rates for the tandem processes of cracking and alkylation are primarily governed by the rates of initiation of carbenium ions and the subsequent intermolecular hydride transfer. Both jointly control the relative rates of cracking and alkylation, thereby determining the overall conversion and selectivity.

Sulfur Switches for Responsive Peptide Materials.

There is considerable recent interest in the synthesis and development of peptide-based materials as mimics of natural biological assemblies that utilize proteins and peptides to form organized structures and develop beneficial properties. Due to their potential compatibility with living organisms, synthetic peptide materials are also being developed for applications such as cell grafting, therapeutic delivery, and implantable diagnostic devices. One desirable feature for such applications is the ability to design materials that can respond to stimuli by changes in their structure or properties under biologically relevant conditions. Peptide and protein assemblies can respond to stimuli, such as changes in temperature, solution pH, ions present in media, or interactions with other biomacromolecules. An exciting area of emerging research is focused on how biology uses the chemistry of sulfur-containing amino acids as a means to regulate biological processes. These concepts have been utilized and expanded in recent years to enable the development of peptide materials with readily switchable properties.The incorporation of sulfur atoms in polypeptides, peptides, and proteins provides unique sites that can be used to alter the physical and biological properties of these materials. Sulfur-containing amino acid residues, most often cysteine and methionine, are able to undergo a variety of selective chemical and enzyme-mediated reactions, which can be broadly characterized as redox or alkylation processes. These reactions often proceed under physiologically relevant conditions, can be reversible, and are significant in that they can alter residue polarity as well as conformations of peptide chains. These sulfur-based reactions are able to switch molecular and macromolecular properties of peptides and proteins in living systems and recently have been applied to synthetic peptide materials. Naturally occurring "sulfur switches" can be reversible or irreversible and are often triggered by enzymatic activity. Sulfur switches in peptide materials can also be triggered in vitro using oxidation/reduction and alkylation as well as photochemical reactions. The application of sulfur switches to peptide materials has greatly expanded the scope of these switches due to the ability to readily incorporate a wide variety of noncanonical sulfur-containing synthetic amino acids.Sulfur switches have been shown to provide considerable potential to reversibly alter peptide material properties under mild physiologically relevant conditions. An important molecular feature of sulfur-containing amino acid residues was found to be the location of sulfur atoms in the side chains. The variation of sulfur atom positions from the backbone by single bond lengths was found to significantly affect polypeptide chain conformations upon oxidation-reduction or alkylation/dealkylation reactions. With the successful adaptation of sulfur switches to peptide materials, future studies can explore how these switches affect how these materials interact with biological systems. This Account provides an overview of the different types of sulfur switch reactions found in biology and their properties and the elaboration of these switches in synthetic systems with a focus on recent developments and applications of reversible sulfur switches in peptide materials.