Engineering Aspects of Industrial Liquid-Phase Air Oxidation of Hydrocarbons

La1-xSrxFeO3-δ Perovskite Oxide Nanoparticles for Low-Temperature Aerobic Oxidation of Isobutane to tert-Butyl Alcohol

The development of reusable solid catalysts based on naturally abundant metal elements for the liquid-phase selective oxidation of light alkanes under mild conditions to obtain desired oxygenated products, such as alcohols and carbonyl compounds, remains a challenge. In this study, various perovskite oxide nanoparticles were synthesized by a sol-gel method using aspartic acid, and the effects of A- and B-site metal cations on the liquid-phase oxidation of isobutane to tert-butyl alcohol with molecular oxygen as the sole oxidant were investigated. Iron-based perovskite oxides containing Fe4+ such as BaFeO3-δ, SrFeO3-δ, and La1-xSrxFeO3-δ exhibited catalytic performance superior to those of other Fe3+- and Fe2+-based iron oxides and Mn-, Ni-, and Co-based perovskite oxides. The partial substitution of Sr for La in LaFeO3 significantly enhanced the catalytic performance and durability. In particular, the La0.8Sr0.2FeO3-δ catalyst could be recovered by simple filtration and reused several times without an obvious loss of its high catalytic performance, whereas the recovered BaFeO3-δ and SrFeO3-δ catalysts were almost inactive. La0.8Sr0.2FeO3-δ promoted the selective oxidation of isobutane even under mild conditions (60 °C), and the catalytic activity was comparable to that of homogeneous systems, including halogenated metalloporphyrin complexes. On the basis of mechanistic studies, including the effect of Sr substitution in La1-xSrxFeO3-δ on surface redox reactions, the present oxidation proceeds via a radical-mediated oxidation mechanism, and the surface-mixed Fe3+/Fe4+ valence states of La1-xSrxFeO3-δ nanoparticles likely play an important role in promoting C-H activation of isobutane as well as decomposition of tert-butyl hydroperoxide.

Water Microdroplets Surrounded by Alcohol Vapor Cause Spontaneous Oxidation of Alcohols to Organic Peroxides

Using real-time mass spectrometric (MS) monitoring, we demonstrate one-step, catalyst-free spontaneous oxidation of various alcohols (ROH) to key reactive intermediates for the formation of ROO- compounds on the surface of water microdroplets surrounded by alcohol vapor, carried out under ambient conditions. These organic peroxides (POs) can act as important secondary organic aerosols (SOA). We used hydrogen-deuterium exchange by spraying D2O instead of H2O to learn about the reaction mechanism, and the results demonstrate the crucial role of the water-air interface in microdroplet chemistry. We find that the formation of POs relies on electron transfer occurring at the microdroplet interface, which generates hydrogen atoms and hydroxyl radicals that lead to a cascade of radical reactions. This electron transfer is believed to be driven by two factors: (1) the emergence of a strong electrostatic potential on the microdroplet's surface; and (2) the partial solvation of ions at the interface. Mass spectra reveal that the formation of POs is dependent on the alcohol structure, with tertiary alcohols showing a higher tendency to form organic peroxides than secondary alcohols, which in turn are more reactive than primary alcohols.

Sustainable Electrochemical Benzylic C-H Oxidation Using MeOH as an Oxygen Source

New methods and strategies for the direct oxidation of benzylic C-H bonds are highly desirable, owing to the importance of ketone motifs in significant organic transformations and the synthesis of valuable molecules, including pharmaceuticals, pesticides, and fine chemicals. Herein, we describe an electrochemical benzylic C-H oxidation strategy for the synthesis of ketones using MeOH as an oxygen source. Inexpensive and safe KBr serves as both an electrolyte and a bromide radical precursor in the reaction. This transformation also offers several advantages such as mild conditions, broad functional group tolerance, and operational simplicity. Mechanistic investigations by control experiments, radical scavenging experiments, electron paramagnetic resonance (EPR), kinetic studies, cyclic voltammetry (CV), and in-situ Fourier transform infrared (FTIR) spectroscopy support a pathway involving the formation and transformation of benzyl methyl ether via hydrogen atom transfer (HAT) and single-electron transfer (SET). The practical application of our strategy is highlighted by the successful synthesis of five pharmaceuticals, namely lenperone, melperone, diphenhydramine, cinnarizine, and flunarizine.

Prospect of Controlled Autoxidation to Produce High-Value Products from the Low-Value Petroleum Fractions

Substantial amounts of low-value light petroleum fractions and low-value heavy petroleum fractions, such as light naphtha, HVGO, and vacuum residue, are generated during the upgrading and refining of conventional and unconventional petroleum resources. The oil industry emphasizes economic diversification, aiming to produce high-value products from these low petroleum fractions through cost-effective and sustainable methods. Controlled autoxidation (oxidation with air) has the potential to produce industrially important oxygenates, including alcohols, and ketones, from the low-value light petroleum fractions. The produced alcohols can also be converted to olefin through catalytic dehydration. Following controlled autoxidation, the low-value heavy petroleum fractions can be utilized to produce value-added products, including carbon fiber precursors. It would reduce the production cost of a highly demandable product, carbon fiber. This review highlights the prospect of developing an alternative, sustainable, and economic method to produce value-added products from the low-value petroleum fractions following a controlled autoxidation approach.

Electrochemical C-H/C-C Bond Oxygenation: A Potential Technology for Plastic Depolymerization

Herein, we provide eco-friendly and safely operated electrocatalytic methods for the selective oxidation directly or with water, air, light, metal catalyst or other mediators serving as the only oxygen supply. Heavy metals, stoichiometric chemical oxidants, or harsh conditions were drawbacks of earlier oxidative cleavage techniques. It has recently come to light that a crucial stage in the deconstruction of plastic waste and the utilization of biomass is the selective activation of inert C(sp3 )-C/H(sp3 ) bonds, which continues to be a significant obstacle in the chemical upcycling of resistant polyolefin waste. An appealing alternative to chemical oxidations using oxygen and catalysts is direct or indirect electrochemical conversion. An essential transition in the chemical and pharmaceutical industries is the electrochemical oxidation of C-H/C-C bonds. In this review, we discuss cutting-edge approaches to chemically recycle commercial plastics and feasible C-C/C-H bonds oxygenation routes for industrial scale-up.

Gas-Phase Characterization of Adipic Acid, 6-Hydroxycaproic Acid, and Their Thermal Decomposition Products by Rotational Spectroscopy

We report the spectroscopic investigation of two bifunctional aliphatic carboxylic acids, namely, adipic acid and 6-hydroxycaproic acid, in the gas phase by combining high-resolution rotational spectroscopy and supersonic expansions. Their pure rotational spectra were successfully identified and characterized. However, due to the low thermal stability of these two chemicals, the measured rotational spectra were significantly congested with transitions corresponding to their decomposition products upon heating. We observed cyclopentanone and adipic anhydride in the spectrum of adipic acid and ε-caprolactone and its monohydrate in the spectrum of 6-hydroxycaproic acid. On the basis of the distinct fingerprints of both carboxylic acids and a series of their decomposition products, the spectra were analyzed in a time-segmented manner. This provides valuable insights into the thermal decomposition mechanisms of these two samples over time, which highlights the robustness of microwave spectroscopy as a potent tool for analyzing complex chemical mixtures in a species-, isomer-, and conformer-selective way.

Efficient Photo-Assisted Thermal Selective Oxidation of Toluene Using N-Doped TiO2

Selective oxidation of toluene is a key reaction to produce high value-added products but remains a big challenge. In this study, we introduce a nitrogen-doped TiO₂ (N-TiO₂) catalyst to create more Ti³⁺ and oxygen vacancy (O_V), which act as active sites for selective oxidation of toluene via activating O₂ to superoxide radical (•O₂^-). Interestingly, the resulting N-TiO₂-2 exhibited an outstanding photo-assisted thermal performance with a product yield of 209.6 mmol·g_cat^-1 and a toluene conversion of 10960.0 μmol·g_cat^-1·h^-1, which are 1.6 and 1.8 times greater than those obtained under thermal catalysis. We showed that the enhanced performance under photo-assisted thermal catalysis was attributed to more active species generation by making full use of photogenerated carriers. Our work suggests a viewpoint to apply a noble-metal-free TiO₂ system in the selective oxidation of toluene under solvent-free conditions.

Facile Ozonation of Light Alkanes to Oxygenates with High Atom Economy in Tunable Condensed Phase at Ambient Temperature

We have demonstrated the oxidation of mixed alkanes (propane, n-butane, and isobutane) by ozone in a condensed phase at ambient temperature and mild pressures (up to 1.3 MPa). Oxygenated products such as alcohols and ketones are formed with a combined molar selectivity of >90%. The ozone and dioxygen partial pressures are controlled such that the gas phase is always outside the flammability envelope. Because the alkane-ozone reaction predominantly occurs in the condensed phase, we are able to harness the unique tunability of ozone concentrations in hydrocarbon-rich liquid phases for facile activation of the light alkanes while also avoiding over-oxidation of the products. Further, adding isobutane and water to the mixed alkane feed significantly enhances ozone utilization and the oxygenate yields. The ability to tune the composition of the condensed media by incorporating liquid additives to direct selectivity is a key to achieving high carbon atom economy, which cannot be achieved in gas-phase ozonations. Even in the liquid phase, without added isobutane and water, combustion products dominate during neat propane ozonation, with CO₂ selectivity being >60%. In contrast, ozonation of a propane+isobutane+water mixture suppresses CO₂ formation to 15% and nearly doubles the yield of isopropanol. A kinetic model based on the formation of a hydrotrioxide intermediate can adequately explain the yields of the observed isobutane ozonation products. Estimated rate constants for the formation of oxygenates suggest that the demonstrated concept has promise for facile and atom-economic conversion of natural gas liquids to valuable oxygenates and broader applications associated with C-H functionalization.

Mesoporous SBA-15 supported gold nanoparticles for solvent-free oxidation of cyclohexane: superior catalytic activity with higher cyclohexanone selectivity

Surface modification of mesoporous SBA-15 with (3-mercaptopropyl) trimethoxysilane greatly enhances its capability to adsorb the tetrachloroauric anion (AuCl₄^-). The calcination of the sample after the adsorption experiment led to the generation of homogeneously dispersed, spherical, single crystalline gold nanoparticles (Au⁰ NPs) of less than 5 nm size, embedded on SBA-15 as observed from the TEM images. The as-prepared SBA-15/Au⁰ nanohybrid material has offered excellent catalytic activity for the selective oxidation of cyclohexane using TBHP as the oxidant in the absence of any solvent. A maximum of 48.7% cyclohexane conversion was achieved and surprisingly, cyclohexanone (K) has much higher selectivity (>95%) than cyclohexanol (A). The hot-filtration study confirmed the leach-resistant characteristics as well as the true heterogeneous catalytic activity of the SBA-15/Au⁰ nanohybrid catalyst. The catalyst was recycled up to four times without significant loss in its catalytic activity.

Effects of Oxygen: Experimental and VTST/DFT Studies on Cumene Autoxidation with Air under Atmospheric Pressure

The mechanism of how oxygen affects cumene autoxidation related to temperature is still bewildering. Kinetic analysis of cumene autoxidation with air at a pressure of 1.0 atm was investigated by experiments and variational transition state theory/DFT. Oxygen was the limiting factor for cumene autoxidation above 100 °C, although it had negligible impacts on cumene autoxidation at 70-100 °C. The kinetic analysis by VTST coupled with DFT calculations proved that {k _6,reverse[ROO^•]}/{k _7,forward[RH]₀ [ROO^•]} > 10³ (70-120 °C), suggesting that ROO^• tended to decompose back to R^• and O₂ rapidly, whereas it was much slower for ROO^• abstracting a hydrogen atom from RH to form ROOH. When the concentration of oxygen was higher than the critical value ([O₂]_critical), it could not significantly affect the equilibrium concentration of ROO^•, which in turn could not affect the autoxidation rate significantly. Besides, the critical oxygen concentration ([O₂]_critical) was exponentially related to 1/T, which was consistent with Hattori's experimental results.

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

A straightforward electro-conversion of cumene into acetophenone has been reported using boron-doped diamond (BDD) electrodes. This particular conversion is driven by the addition reaction of a cathodically generated hydroperoxide anion to an anodically generated cumyl cation, where the BDD’s wide potential window enables the direct anodic oxidation of cumene into the cumyl cation. Since electricity is directly employed as the oxidizing and reducing reagents, the present protocol is easy to use, suitable for scale-up, and inherently safe.

Liquid Phase Oxidation of Hydrocarbons to High-Value Chemicals in Microfluidic Reactors - Prospects and Challenges

Liquid phase oxidation (LPO) of hydrocarbon is an industrially important process to produce petrochemicals and pharmaceuticals. It follows a free radical path having initiation, propagation and termination. The initiation step is slow while the propagation and termination steps are fast. The main challenge of such process is to control product selectivity at an appreciable conversion level. With the advancement of microfluidic reactor technology, it is possible to control the free radical steps. The present contribution critically reviewed the reaction engineering aspects of LPO of hydrocarbon, the influence of microfluidic reactor design and operation on reaction mechanism, conversion and product selectivity. It also outlines the challenges associated with microfluidic reactor operation, and prospects to apply the understanding from microfluidic reactors in few sectors. The understanding from the free radical oxidation process can also be applied to any other free radical processes.

Plasmonic O2 dissociation and spillover expedite selective oxidation of primary C-H bonds

Manipulating O₂ activation via nanosynthetic chemistry is critical in many oxidation reactions central to environmental remediation and chemical synthesis. Based on a carefully designed plasmonic Ru/TiO_2−x catalyst, we first report a room-temperature O₂ dissociation and spillover mechanism that expedites the “dream reaction” of selective primary C–H bond activation. Under visible light, surface plasmons excited in the negatively charged Ru nanoparticles decay into hot electrons, triggering spontaneous O₂ dissociation to reactive atomic ˙O. Acceptor-like oxygen vacancies confined at the Ru–TiO₂ interface free Ru from oxygen-poisoning by kinetically boosting the spillover of ˙O from Ru to TiO₂. Evidenced by an exclusive isotopic O-transfer from ¹⁸O₂ to oxygenated products, ˙O displays a synergistic action with native ˙O₂⁻ on TiO₂ that oxidizes toluene and related alkyl aromatics to aromatic acids with extremely high selectivity. We believe the intelligent catalyst design for desirable O₂ activation will contribute viable routes for synthesizing industrially important organic compounds.

Room-temperature O₂ dissociation and spillover, as driven by plasmonic Ru on oxygen-deficient TiO₂, expedite the selective oxidation of primary C–H bonds in alkyl aromatics for synthesizing industrially important organic compounds.

Ten Years of Glory in the α-Functionalizations of Acetophenones: Progress Through Kornblum Oxidation and C-H Functionalization

This review article focuses on the α-functionalization of acetophenones involving Kornblum oxidation and C-H functionalizations. Although various other strategies, such as classical approaches, enamine approaches and umpolung strategy are also known for this functionalization, here we discuss mainly the Kornblum oxidation approach and C-H functionalization strategy as they have advantages over the others. In Kornblum oxidation, the reaction uses iodine and dimethylsulfoxide and proceeds through the formation of arylglyoxal as the key intermediate. In C-H functionalization, the reaction requires metal, or metal-free catalyst, and generates radical intermediate in most cases. α-Functionalization of acetophenones is very important because of their huge applications in the synthesis of various natural products and pharmaceuticals and, therefore, a number of research articles have been published in this area. However, no review articles are available so far. In this article, we present a succinct discussion of various important and novel reactions, along with their mechanisms, published since 2012 to date. We believe that this first review article in this field will give readers one-stop information on this topic and encourage further intriguing work in this area.

Development of a Detailed Kinetic Model for the Oxidation of n-Butane in the Liquid Phase

The chemistry underlying liquid-phase oxidation of organic compounds, the main cause of their aging, is characterized by a free-radical chain reaction mechanism. The rigorous simulation of these phenomena requires the use of detailed kinetic models that contain thousands of species and reactions. The development of such models for the liquid phase remains a challenge as solvent-dependent thermokinetic parameters have to be provided for all the species and reactions of the model. Therefore, accurate and high-throughput methods to generate these data are required. In this work, we propose new methods to generate these data, and we apply them for the development of a detailed chemical kinetic model for n-butane autoxidation, which is then validated against literature data. Our approach for model development is based on the work of Jalan et al. [J. Phys. Chem. B 2013, 117, 2955-2970] who used Gibbs free energies of solvation [ΔsolvG(T)] to correct the data of the gas-phase kinetic model. In our approach, an equation of state (EoS) is used to compute ΔsolvG as a function of temperature for all the chemical species in the mechanism. Currently, ΔsolvG(T) of free radicals cannot be computed with an EoS and it was calculated for their parent molecule (H-atom added on the radical site). Theoretical calculations with the implicit solvent model were performed to quantify the impact of this assumption and showed that it is acceptable for radicals in n-butane and probably in all n-alkanes. New rate rules were proposed for the most important reactions of the model, based on theoretical calculations and the literature data. The developed detailed kinetic model for n-butane autoxidation is the first proposed model in the literature and was validated against the experimental data from the literature. Simulations showed that the main autoxidation products, sec-butyl hydroperoxides and 2-butanol, are produced from H-abstractions from n-butane by sec-C4H9OO radicals and the C4H9OO + C4H9OO reaction, respectively. The uncertainty of the product ratio ("butanone + 2-butanol"/"2-butoxy + 2-butoxy") of the latter reaction remains high in the literature, and our simulations suggest a 1:1 ratio in n-butane solvent.

A new highly active La2O3-CuO-MgO catalyst for the synthesis of cumyl peroxide by catalytic oxidation

In this study, different magnesium, copper, lanthanide single metal, and composite multimetal oxide catalysts were prepared via the coprecipitation route for the aerobic oxidation of cumene into cumene hydroperoxide. All catalysts were characterized using several analytical techniques, including XRD, SEM, EDS, FT-IR, BET, CO₂-TPD, XPS, and TG-DTG. La₂O₃–CuO–MgO shows higher oxidation activity and yield than other catalysts. The results of XRD and SEM studies show that the copper and magnesium particles in the catalyst are smaller in size and have a distribution over a larger area due to the introduction of the lanthanum element. The CO₂-TPD results confirmed that the catalyst has more alkali density and alkali strength, which can excite active sites and prevent the decomposition of cumene hydroperoxide. XPS results show that due to the promotional effect of La₂O₃, there are more lattice and active oxygen species in the catalyst, which can effectively utilize the lattice defects under the strong interaction between metal oxides for rapid adsorption and activation, thus improving the oxidation performance. Besides, La₂O₃–CuO–MgO exhibits good stability and crystalline structure due to its high oxygen mobility inhibiting coking during the cycle stability test. Finally, the possible reaction pathway and promotional mechanism on La₂O₃–CuO–MgO in cumene oxidation are proposed. We expect this study to shed more light on the nature of the surface-active site(s) of La₂O₃–CuO–MgO catalyst for cumene oxidation and the development of heterogeneous catalysts with high activity in a wide range of applications.

The La₂O₃–CuO–MgO catalyst acts on the oxidation of cumene and shows excellent catalytic activity through the coordination of surface and interior.

Asymmetric Total Synthesis of (-)-Spirochensilide A, Part 1: Diastereoselective Synthesis of the ABCD Ring and Stereoselective Total Synthesis of 13(R)-Demethyl Spirochensilide A

A concise and diastereoselective construction of the ABCD ring system of spirochensilide A is described. The key steps of this synthesis are a semipinacol rearrangement reaction to stereoselectively construct the AB ring system bearing two vicinal quaternary chiral centers and a Co-mediated Pauson-Khand reaction to form the spiro-based bicyclic CD ring system. This chemistry leads to the stereoselective synthesis of 13(R)-demethyl spirochensilide A, paving the way for the first asymmetric total synthesis of (-)-spirochensilide A.

A recyclable cobalt(iii)–ammonia complex catalyst for catalytic epoxidation of olefins with air as the oxidant

A recyclable [Co(NH₃)₆]Cl₃ complex was synthesized to catalyze the epoxidation of α-pinene. With air as the oxidant, [Co(NH₃)₆]Cl₃ obtained 97.4% conversion of α-pinene and 98.3% selectivity of epoxide.

Tunable selectivity of phenol hydrogenation to cyclohexane or cyclohexanol by a solvent-driven effect over a bifunctional Pd/NaY catalyst

Hydrogenation of phenol is an important strategy to produce cyclohexane or cyclohexanol as both of them are raw materials for the synthesis of nylon-6 and nylon-66.

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

Photochemical activation routes are gaining the attention of the scientific community since they can offer an alternative to the traditional chemical industry that mainly utilizes thermochemical activation of molecules. Photoreactions are fast and selective, which would potentially reduce the downstream costs significantly if the process is optimized properly. With the transition towards green chemistry, the traditional batch photoreactor operation is becoming abundant in this field. Process intensification efforts led to micro- and mesostructured flow photoreactors. In this work, we are reviewing structured photoreactors by elaborating on the bottleneck of this field: the development of an efficient scale-up strategy. In line with this, micro- and mesostructured bench-scale photoreactors were evaluated based on a new benchmark called photochemical space time yield (mol·day⁻¹·kW⁻¹), which takes into account the energy efficiency of the photoreactors. It was manifested that along with the selection of the photoreactor dimensions and an appropriate light source, optimization of the process conditions, such as the residence time and the concentration of the photoactive molecule is also crucial for an efficient photoreactor operation. In this paper, we are aiming to give a comprehensive understanding for scale-up strategies by benchmarking selected photoreactors and by discussing transport phenomena in several other photoreactors.

AgNPs encapsulated by an amine-functionalized polymer nanocatalyst for CO2fixation as a carboxylic acid and the oxidation of cyclohexane under ambient conditions

A novel catalyst comprising Ag NPs grafted to a porous polystyrene material was synthesized for the production of valuable propiolic acid derivativesviaCO₂(1 atm) incorporation, and the oxidation of cyclohexane under ambient reaction conditions.

Room-temperature air oxidation of organic pollutants via electrocatalysis by nanoscaled Co-CoO on graphite felt anode

Oxygen (O₂) in air is an eco-friendly and economical oxidant. However, its activation is an energy-intensive process requiring high operation temperature. Herein, we report the synthesis of nanoscaled Co-CoO on a graphite felt (GF) as an anode material for electrocatalytic wet air oxidation (ECWAO) of water contaminants at room temperature. Such an ECWAO process shows extensive effectiveness in mineralizing a variety of biorefractory organic pollutants. A probe pollutant, bisphenol A (BPA), is rapidly degraded in 180 min with mineralization efficiencies higher than 85% over a wide pH range from 3.0 to 11.0. The Co-CoO/GF electrode exhibits excellent stability in the ECWAO process, without loss of activity and leaching of metal. The ECWAO process is confirmed to be initiated by the electrochemical activation of O₂ through a non-radical pathway. The CoO on the surface of Co nanoparticle is identified as the catalytically active site, at which O₂ molecules are first converted to chemisorbed oxygen species and then electrochemically oxidized to their activated states. The ECWAO process with the Co-CoO/GF electrode presents the merits of high efficiency, low energy input and environmental friendliness, and has a great potential for practical wastewater treatment.

Ruthenium Trichloride Catalyst in Water: Ru Colloids versus Ru Dimer Characterization Investigations

An easy-to-prepare ruthenium catalyst obtained from ruthenium(III) trichloride in water demonstrates efficient performances in the oxidation of several cycloalkanes with high selectivity toward the ketone. In this work, several physicochemical techniques were used to demonstrate the real nature of the ruthenium salt still unknown in water and to define the active species for this Csp³-H bond functionalization. From transmission electron microscopy analyses corroborated by SAXS analyses, spherical nanoobjects were observed with an average diameter of 1.75 nm, thus being in favor of the formation of reduced species. However, further investigations, based on X-ray scattering and absorption analyses, showed no evidence of the presence of a metallic Ru-Ru bond, proof of zerovalent nanoparticles, but the existence of Ru-O and Ru-Cl bonds, and thus the formation of a water-soluble complex. The EXAFS (extended X-ray absorption fine structure) spectra revealed the presence of an oxygen-bridged diruthenium complex [Ru(OH) _xCl_{3- x}]₂(μ-O) with a high oxidation state in agreement with catalytic results. This study constitutes a significant advance to determine the true nature of the RuCl₃·3H₂O salt in water and proves once again the invasive nature of the electron beam in microscopy experiments, routinely used in nanochemistry.

N-Doped carbon nanofibers derived from bacterial cellulose as an excellent metal-free catalyst for selective oxidation of arylalkanes

N-Doped carbon nanofibers derived from one-step pyrolysis of low-cost bacterial cellulose with the assistance of urea were an excellent metal-free carbocatalyst for selective oxidation of arylalkanes.

Advances in Nanostructured Metal-Encapsulated Porous Organic-Polymer Composites for Catalyzed Organic Chemical Synthesis

Porous organic polymers (POPs) are of growing research interest owing to their high surface areas, stabilities, controllable chemical configurations, and tunable pore volumes. The molecular nanoarchitecture of POP provides metal or metal oxide binding sites, which is promising for the development of advanced heterogeneous catalysts. This article highlights the development of numerous kinds of POPs and key achievements to date, including their functionalization and incorporation of nanoparticles into their framework structures, characterization methods that are predominantly in use for POP-based materials, and their applications as catalysts in several reactions. Scientists today are capable of preparing POP-based materials that show good selectivity, activity, durability, and recoverability, which can help overcome many of the current environmental and industrial problems. These POP-based materials exhibit enhanced catalytic activities for diverse reactions, including coupling, hydrogenation, and acid catalysis.