Heterogeneous Reaction Systems Research Articles

Kinetics of continuously catalyzed peroxymonosulfate in a fixed-bed reactor

Most studies have been conducted in batch reactors. Therefore, understanding the catalytic reaction kinetics and mass transfer in continuous catalytic reactors is essential for the design of heterogeneous catalysts and optimisation of catalytic degradation processes in heterogeneous systems. In this research, granular catalysts (Co-600/AlSi-0.25/AP) is used to investigate the kinetic constants and mass transfer resistance for the continuous catalytic decomposition of peroxymonosulfate (PMS) and degradation of p-nitrophenol (PNP) in a fixed bed reactor. The flow rate is 5 mL/min and reaction temperature is 30 °C, intrinsic kinetic constants of PMS decomposition and PNP degradation are 48 and 195 kg−1·min−1·L, respectively, which are 20–30 times of the apparent kinetic constants of PMS decomposition and PNP degradation in fixed bed reactors, respectively. The decomposition rates of PMS and PNP are controlled by mass transfer, and the reaction takes place in the diffusion-controlled regime. The mass transfer kinetic model based on the plug-flow model shows a good agreement between the calculated data and the experimental data. Which indicate that PMS decomposition and pollutant degradation in a fixed-bed reactor can be predicted by mass transfer kinetic modelling, guide the design of catalysts and the optimisation of heterogeneous catalytic reaction system in a fixed-bed reactor.

A CIRCULAR ECONOMY APPROACH TO PRODUCE LOW-COST BIODIESEL USING AGRO-INDUSTRIAL AND PACKING WASTES FROM MEXICO: VALORIZATION, HOMOGENEOUS AND HETEROGENEOUS REACTION ROUTES AND PRODUCT CHARACTERIZATION

This manuscript describes a circular economy approach to produce low-cost biodiesel using Tetra Pak (TP) and Mexican biomass wastes. Lipids were extracted from non-edible biomass with hexane. Corozo seeds contained 53 wt% lipids, while remaining biomass had <5 wt%. Corozo seed oil was selected to produce biodiesel with both homogeneous and heterogeneous reaction systems. A heterogeneous catalyst was synthesized from TP and its performance was compared with KOH in homogeneous systems using corozo and soybean oils. The best reaction conditions were identified through the Signal/Noise ratio analysis. TP catalyst achieved biodiesel yields of 12.7-98.11% (corozo) and 87.0-98.4% (soybean), while KOH systems showed 7.2-96.3% and 64.6-98.5%, respectively. These reactive systems were endothermic and fit to pseudo-second order kinetic model. Activation energies for KOH-catalyzed systems were 86.89 (corozo) and 43.72 (soybean) kJ/mol, while TP-catalyzed systems showed 78.31 and 105.68 kJ/mol, respectively. TP catalyst reuse was tested, and the loss of catalytic activity was attributed to active sites poisoning. Biomass, catalysts, and reaction products were characterized (e.g., FTIR, ICP, XRD, EDX-SEM, WDXRF, XPS, basicity and nitrogen adsorption isotherms). The TP catalyst showed competitive performance with respect to KOH, contributing to a sustainable biodiesel production chain viable for commercial implementation in Mexico.

New insights into the quantiffcation of Fe(IV) using methyl phenyl sulfoxide (PMSO) as probe in the iron-based heterogeneous catalyst activated persulfate process

Ferryl ions (Fe(IV)) are often thought to play an important role in iron-based advanced oxidation processes (AOPs), and their presence is typically inferred through the unique pathway of methyl phenyl sulfoxide (PMSO) conversion to methyl phenyl sulfone (PMSO2). Here, we first employed probe method by degrading the mixed system containing PMSO, benzoic acid (BA), nitrobenzene (NB) to analyze the steady-state concentration of Fe (IV) in the iron-based heterogeneous persulfate reaction system. In addition, studies were conducted on the direct oxidation of PMSO by different oxidants under different pH conditions, and the results showed that peroxymonosulfate (PMS), sodium hypochlorite (NaClO) and sodium periodate (PI) can directly oxidize PMSO and convert it into PMSO2. Furthermore, the influence of different types of iron salts and biomass on the prepared iron-biochar (Fe-BC) for the activation of persulfate on degradation of PMSO and the formation of PMSO2 was also investigated. This study may provide new insights into the use of PMSO as a probe for the analysis of Fe(IV) in heterogeneous reaction systems.

Development of Organocatalytic Darzens Reactions Exploiting the Cyclopropenimine Superbase.

A truly organocatalytic approach to the Darzens reaction affording α,β-epoxy carbonyl compounds in good yields was developed taking advantage of the high basic strength and low nucleophilicity of cyclopropenimine superbases. The catalytic active free base can easily be generated in situ from its hydrochloride salt and maintained in the active deprotonated form by performing the reactions in a heterogeneous reaction system in the presence of excess potassium carbonate as a sacrificial base.

Fast and Selective Main-Chain Scission of Vinyl Polymers Using the Domino Reaction in the Alternating Sequence for Transesterification.

This communication reports on vinyl polymers capable of selective and fast main-chain scission (MCS). The trick is the domino reaction in an alternating sequence of methyl 2-(trimethylsiloxymethyl)acrylate and 5,6-benzo-2-methylene-1,3-dioxepane, a cyclic ketene acetal for radical ring-opening polymerization. Removal of the trimethylsilyl group using Bu4N+·F- readily led to MCS via irreversible transesterification of the ester backbone, affording a five-membered lactone fragment. The molar mass decreased drastically within 5 min, and no side reactions were observed. Control experiments suggest that the formation of a five-membered ring via a domino reaction is critical for fast and selective MCS. The terpolymers with methyl methacrylate and styrene also exhibited a large decrease in molar mass within 5 min. In addition, MCS was also observed for the heterogeneous reaction system in acidic aqueous media; treatment of the binary copolymer in a 50 wt % acetic acid solution resulted in a significant decrease in molar mass after 30 min. These results suggest efficient construction of degradable sites using a binary monomer system corresponding to the pendant trigger and ester backbone. Because this molecular design using a binary monomer system provides selective and fast MCS for terpolymers containing other vinyl monomers, it can provide various degradable vinyl polymers.

Copper‐based nanocatalysts toward chemoselective hydrogenation reaction

AbstractCu‐based catalysts are widely used in various heterogeneous catalytic reaction systems, the precise control of their electronic structure is an intrinsic requirement for the rational design of metal catalysts, and it is also an important basis for clarifying their structure‐activity relationships. Changing the electronic structure of Cu‐based catalysts is an important way to improve the catalytic hydrogenation performance of Cu‐based catalysts by controlling the adsorption intensity between the reaction adsorbate and the active center. In this paper, the application of selective hydrogenation of Cu‐based catalysts is reviewed, with a special emphasis on the selective catalytic hydrogenation reduction of p‐nitrostyrene and CO2. This review particularly emphasizes the application of Cu‐based catalysts in the field of selective hydrogenation and discusses the influence of their different properties on selective hydrogenation performance.

Effective diffusional limitation modeling of a heterogeneous reaction system for computational fluid dynamics application

Diffusional limitation of heterogeneous reaction catalysts is typically fitted or over-generalized without considering the catalyst’s physical parameters upon conducting computational fluid dynamics (CFD) analysis of an industrial-scale chemical reactor. Fitting and over-generalization are done to meet computational cost constraints. However, this reduces the reliability of local thermodynamic state analysis and application of calculated results. This study proposes an effective catalytic diffusion-limited model for reliable and cost-effective three-dimensional CFD simulations to overcome such difficulties. The proposed model utilizes simplified equations to compute the diffusional limitation by incorporating the physical parameters of the catalyst. The model is validated using Ni-based cylindrical catalyst pellets for steam–methane reforming and ammonia decomposition reactions, with in-house experiments supporting the fidelity of the model. For practical implementation, the model is applied to three-dimensional CFD simulations of a commercial-scale solid oxide fuel cell (SOFC) hotbox housing a large-scale reformer. Furthermore, a parametric study for inlet gas temperatures and catalyst size is carried out, which provides useful insights into how operating conditions and catalysts affect the transport phenomena and local thermodynamic state of the SOFC hotbox. Consequently, the practicality and versatility of the presented model are established through experiments and simulations.

Liquid‐solid‐Interpenetration Surface Reconstruction of Monodisperse Water Stabilized CsPbBr3/CsPb2Br5 Core/Shell Perovskite Nanocrystals

AbstractAll‐inorganic lead halide perovskite nanocrystals (NCs) have shown great potential in various optoelectronic device applications due to their excellent optoelectronic properties, but their poor stability remains a key obstacle to widespread application. The preparation of core/shell NCs is developed to improve their stability, but most of the coating for single NCs is incomplete, and the crystal orientation and interface binding of core/shell structures are still unclear. Here, a surface reconstruction strategy to synthesize CsPbBr3/CsPb2Br5 core/shell NCs with uniform coating structure is reported. The concentration of [PbBr8]6− monomer in the system is regulated by creating local low H2O concentration conditions to balance the erosion of perovskite by water and the overall heterogeneous nucleation reaction system, resulting in single encapsulated and well‐edged perovskite core/shell NCs. More importantly, advanced characterization tools are used to reveal the core/shell structural features of CsPbBr3/CsPb2Br5 core/shell NCs at the atomic scale, which has not been reported before, and the interface matching of the two‐phase binding is simulated by density functional theory calculations, which confirm that the CsPb2Br5 (116) facet can bind to the CsPbBr3 (100) facet with the lowest binding energy. The prepared core/shell perovskite NCs can still retain photoluminescence emission after &gt;30 days in water.

High Density Poly(ionic liquid)s with Spatial Structure Regulation for Efficient Carbon Dioxide Cycloaddition

AbstractThe synthesis of cyclic carbonate from CO2 and epoxide is one of the valid routes in line with atomic economy to achieve CO2 conversion. Combining the advantages of high activity and easy separation for heterogeneous catalytic reaction system, a series of heterogeneous catalysts poly(ionic liquid)s with high ionic density (HDPILs) were designed and synthesized. Looser structures and high ionic density were obtained by using muti‐center ionic liquids with different number of substituents as cross‐linking agents. Ply[PhSVIM]Br, the copolymerized HDPILs with six substituents on the benzene ring was optimal. The catalyst exhibited excellent catalytic performance for CO2 cycloaddition with 98 % conversion and 99 % selectivity under optimal conditions. These HDPILs have comparable catalytic activity to homogeneous catalysts and convenient product separability. Particularly, combining XPS and DFT, a structural performance relationship was revealed, the multi‐center ionic liquids used instead of the traditional crosslinking agent as the polymeric backbone can contribute to the reduction of the anion and cation binding energy (BE) and freeing of Br−, which leads to efficient catalytic activity. This study provides a novel strategy for developing a highly efficient catalysts for CO2 conversion to high value products.

Deep degradation of sulfamethoxazole by the Fe-Co/γ-Al2O3-catalysed photo-Fenton system

ABSTRACT The heterogeneous photo-Fenton system using Fe-Co/γ-Al2O3 as a catalyst was applied in the study of sulfamethoxazole(SMX) degradation. The morphology, structure, elemental composition and metal valence distribution of Fe-Co/γ-Al2O3 were found to be relatively stable before and after the reaction. The highest SMX degradation efficiency and mineralization (The ratio of organic matter being oxidized to carbon dioxide and water) were obtained under the conditions of 15% Fe-Co loading rate, 1:1 mass ratio of Fe and Co, 1 g/L catalyst dosage, 1.5 mL 30% H2O2 dosage, 18 W UV lamp power and 60 min reaction time, which were 98% and 66%, respectively. Radical quenching experiments and electronic paramagnetic resonance (EPR) characterization revealed that ·OH played an important role in the degradation and mineralization SMX in the Fe-Co/γ-Al2O3 heterogeneous photo-Fenton system. Combined with the analysis of N, S and intermediate products, there may be three degradation pathways of SMX in the heterogeneous photo-Fenton system. This work provides a technical reference for realizing the efficient degradation and mineralization of SMX in a heterogeneous photo-Fenton reaction system.

Nitration of o-xylene in the microreactor: Reaction kinetics and process intensification

Nitration reactions are extensively studied in organic synthesis despite their notorious dangers, high reaction rates, and heterogeneous reaction systems. To date, most industrial nitration reactions rely on conventional batch reactors characterized by low mass transfer rates and limited reaction conditions. In contrast, microreactors represent a valuable technology for intensifying such nitration reactions. In this work, we established a continuous flow system of o-xylene nitration and determined the kinetics and mass transfer. The effects of mixing performance, nitric acid concentration, molar ratio, reaction temperature, and residence time on the process safety were investigated separately. The experimental data is supported by dimensionless number calculations, providing a more comprehensive understanding of the nitration reaction's transport and reaction performance in a heart-shaped microreactor. Remarkably, the residence time of the heart-shaped microreactor was reduced by an order of magnitude, while the volumetric mass transfer coefficient was improved by several orders of magnitude compared to conventional stirred tank reactors. Moreover, the spent nitric acid could be efficiently recovered and reused after concentration, further enhancing the sustainability and cost-effectiveness of the process. Our findings demonstrate the significant potential of microreactors for intensifying nitration reactions and paving the way for the design and optimization of more efficient and safer synthetic processes.

Bio‐inspired Porous Composite Electrode for Enhanced Mass Transfer and Electrochemical Water Purification by Modifying Local Flow Pattern

AbstractPorous electrodes offer a new opportunity for flow‐through electrochemical water purification, but their irregular porous‐structure makes the local flow pattern and mass transfer performance inhomogeneous, unpredictable, and uncontrollable. In this study, a bio‐inspired design is reported for porous electrode by learning the micro‐scale architectures of the wings of butterfly and owl based on analogy between heterogeneous mass transfer and sound absorption. Results demonstrate that combining gyroid and perforated plate can produce strong periodic vortex and inertial flow in interpenetrating channels even at laminar flow region. This enables homogeneous, predictable and controllable flow patterns and enhanced mass transfer, which can be explained by uniformity analysis and physical field synergy. Based on experimental tests on Cu electrode fabricated by selective laser melting, the composite gyroid electrode generates the limiting current density of 83% higher than random porous‐structured electrode, accounting for nitrate removal as high as 95% by electrochemical denitrification. This study represents a paradigm shift to advance design for porous architectures by learning experiences of hydrodynamic behaviors from nature. In this way, it is feasible to enhance mass transfer by modifying local flow patterns on pore scale, which may have broader implications that extend to other heterogeneous reaction systems.

Ligand-assisted heterogeneous catalytic H2O2 activation for pollutant degradation: The trade-off between coordination site passivation and adjacent site activation

Ligand modification is an effective and universal strategy to enhance the sluggish surface reaction kinetic in the heterogeneous Fenton system. However, the mechanistic for the promotion effect concerning the complex surface adsorption/activation processes remains unrevealed. Herein, we find that the catalytic H2O2 activation ability of BiFeO3 can be significantly enhanced by EDTA and other polycarboxylate ligands. The complexing effect of EDTA enhances the activation rate of H2O2 via decreasing the redox potential of the FeIII/FeII pair, also remarkably improves the utilization efficiency of H2O2 via preserving the electron-rich FeII under the attack of O2•/HO2•. More importantly, based on kinetic analyses and theoretical calculations, we reveal that the active site for H2O2 activation on the EDTA-adsorbed BiFeO3 surface is the adjacent free FeIII, rather than the EDTA complexing FeIII and the non-adjacent free FeIII. A unique dual effect mechanism of EDTA on the heterogeneous Fenton reaction via the coordination site passivation and adjacent site activation is elucidated. This work clarifies the microcosmic role of ligands in governing the catalytic activity of the surface active site, also provide a significant guidance to rationally develop efficient ligand-assisted heterogeneous reaction system for pollutant degradation.

Phthalimide based new photocatalysts featured with highly selective photodegradation of azo-dyes and good photocatalytic activity in both homogeneous and heterogeneous systems

• Phthalimide (PI) preferentially photodegrades azo dye in mixture with non-azo dye. • PI shows good photocatalytic activity in homogeneous and heterogeneous system. • Halogenation of PI tunes the photocatalytic performance. • PI with selective photodegradation of dye is promising in environment remediation. Selective degradation of the target pollutants allows delicate manipulation of the environmental remediation process via photocatalysis, and has attracted much attention in recent years. Herein, we report the preparation and photocatalytic behaviors of an organic semiconductor of phthalimide (PI). It is found that PI could effectively degrade the azo-dyes under UV irradiation in either heterogeneous or homogeneous reaction system, which is rarely reported for the photodegradation of the dyes. In comparison, the halogenation of PI has an adverse effect on the photocatalytic activity of corresponding PI derivatives. Moreover, PI is used to photodegrade the mixtures of azo-dyes and non-azo dyes. It is found that PI achieves highly selective photodegradation of the azo-dyes in a heterogeneous reaction system, while its halogenated derivatives exhibit lower selectivity. By contrast, no preferential photodegradation is observed in the homogeneous methanol solution. It is proposed that the regular π-π stacking conjugated structure of the PI based molecules are responsible for the selective photodegradation behaviors. The work offers new approaches for the development of advanced organic molecule photocatalysts with desirable features including selective photodegradation and efficient degradation of dyes in both heterogeneous and homogeneous photocatalysis.

PETpyrolysis and hydrolysis mechanism in the fixed pyrolyzer

AbstractIn the conventional polyethylene terephthalate (PET) pyrolysis process, the formation of char by excessive pyrolysis is mainly due to the dehydration mechanism, so water is considered an auxiliary agent that can effectively inhibit excessive pyrolysis. The preparation of terephthalic acid (TPA) by steam‐assisted pyrolysis of PET is an effective method to achieve closed‐loop recycling of waste PET. To ensure that the reaction is mild enough to reduce excessive cracking products such as char and benzoic acid and thus increase the yield of TPA, it is critical to reduce the reaction rate while maintaining a sufficient excess steam coefficient. Under the optimal operating conditions, when the temperature rise rate was 0.5 °C min−1and the excess steam coefficient was 150, the yield of TPA was 72.5 wt.%, and the purity was 85.5%. Noticeably, the steam‐assisted pyrolysis system is a heterogeneous reaction system whose reaction mechanism is different from the conventional hydrolysis and pyrolysis reactions and has a unique reaction path. The mechanistic study indicates that, in addition to the thermal cracking of PET molecules occurring in conventional pyrolysis, hydroxyl attack and transfer, and supplementation of benzene ring hydrogen also occur between water and intermediate molecules. Meanwhile, it has also been proven that the intermolecular hydrogen transfer between intermediate molecules and water molecules is the key to reduce the intensity of the reaction and inhibit the formation of char. This discovery illustrates the mechanism of the reaction between water and PET in the steam‐assisted pyrolysis process in the fixed pyrolyzer and justifies the distinction between it and the pyrolysis and hydrolysis processes of PET. It provides a theoretical basis for optimizing the pyrolysis process of PET, which is essential for the industrialization of TPA preparation from PET steam‐assisted pyrolysis.

Visible Light-Induced Reactive Yellow 145 Discoloration: Structural and Photocatalytic Studies of Graphene Quantum Dot-Incorporated TiO2.

Visible light-induced photocatalytic treatment of organic waste is considered a green and efficient route. This study explored the structural and photocatalytic performance of graphene quantum dot (GQD)-incorporated TiO2 nanocomposites to treat reactive yellow 145 (RY145) dye. For the effective removal of the RY145, efforts were made to better understand the kinetics of the process and optimization of the treatment parameters. Different GQD-doped TiO2 nanocomposites were synthesized employing the sol-gel method. Physicochemical characteristics of the synthesized nanocomposites were studied through FTIR, XRD, UV-visible spectroscopy, SEM, and EDX. Screening studies were conducted for synthesis and reaction optimization. The results indicated that GQD-TiO2 significantly enhanced the photocatalytic discoloration for RY145 dye. Among the synthesized nanocomposites, 15GQD-TiO2 calcined at 300 exhibited 99.3% RY145 discoloration in 30 min under visible light irradiation. Following the pseudo-first-order reaction, the photocatalytic reaction constant K app progressively declined with an increase in the concentration of RY145. The heterogeneous reaction system conformed to the Langmuir-Hinshelwood isotherm, as indicated by the K C (1.08 mg L-1 min-1) and the K LH (0.18 L mg-1) values. O2 •- was found to be the major contributor in GQD-TiO2-300 to decolorize RY154, while TiO2 and GQDs played a vital role in generation of electrons and holes. Additionally, after recycling to the seventh cycle, only 9% decline in photocatalytic performance was observed for the synthesized nanocomposite.

Construction of underwater‐superaerophilic Pd‐CNTs/fluorosilane composite for enhancing heterogeneous catalytic hydrogenation reactions

Wettability is an important property of solid surfaces, superwetting materials can be prepared by controlling the surface morphology and surface energy. In recent years, superwetting materials have been researched and used widely in the fields of self‐cleaning, anti‐fogging, microfluidics, and oil–water separation, but few studies about superwetting materials in chemical reactions have been conducted. In the multiphase reaction, the low solubility and diffusion rate of gas lead to inferior mass transfer, which restricts the reaction kinetics and reduces the reaction rate. Therefore, it may be a breakthrough to make the solid surface obtain underwater superaerophilicity. In this paper, 1H,1H,2H,2H‐perfluorooctyltriethoxysilane (POTS) with low surface energy was constructed on the palladium‐carbon nanotubes (Pd‐CNTs), as‐prepared Pd‐CNTs/POTS composite has excellent hydrophobicity and underwater superaerophilicity. When Pd‐CNTs/POTS composite was utilized in the catalytic hydrogenation, Pd‐CNTs/POTS composite shows higher catalytic activity than Pd‐CNTs; the higher catalytic performance is attributed to the underwater superaerophilicity, which enables gaseous hydrogen to rapidly accumulate on the surface of material, increasing the gas–liquid–solid reaction interface formed. The strategy looks forward to providing a new way for developing novel and efficient heterogeneous catalysts and reaction systems.

Distribution Characteristics of Multiphysics around the Bubble on the Surface of Photoelectrode

In the heterogeneous photocatalytic reaction systems, the evolution of bubbles on the catalyst surface is a complex process that depends on multiple factors, such as the solid–liquid interface structure, solution properties of the reaction system, and multiphysics interactions, and directly affects energy and mass transport processes. This study investigated the multiphysics distribution around a bubble and the bubble detachment characteristics on the surface of a TiO2 photoelectrode during photoelectrocatalytic water splitting. The bubble diameter had an effect on the distribution of the light field in the system, affecting the temperature and flow distributions of the electrolyte around the bubble. Marangoni convection was induced by the inhomogeneous temperature distribution along the bubble interface, which enhanced the heat and mass transfer near the reaction site. It was also demonstrated that an increase in laser power increased Marangoni convection on the bubble surface, thus delaying bubble detachment. A force model for predicting the bubble detachment diameter that considered the coupling effect between the light, temperature, and flow fields was developed. The predicted bubble detachment diameters agreed well with the experimental results within an error of ±10%.

Enhancement of fructosyltransferase stability by immobilization on polyhydroxybutyrate and glutaraldehyde‐activated polyhydroxybutyrate for fructooligosaccharides production

AbstractBACKGROUNDFructosyltransferase (FTase) enzyme is an important biocatalyst for fructooligossaccaride (FOS) production, but it has low stability in soluble form. The aim of this work was to analyze the stability and kinetics of an fructosyltransferase (FTase E.C.2.4.1.9) from Aspergillus oryzae IPT‐301 immobilized on polyhydroxybutyrate (PHB) and glutaraldehyde‐activated polyhydroxybutyrate (GLU‐PHB).RESULTSThe immobilization yields of the FTase on PHB and GLU‐PHB were about 41% and 55%, respectively. The recovery activities of the FTase immobilized on PHB and GLU‐PHB were about 17% and 11%, respectively. At 30 °C, the FTase immobilized on GLU‐PHB showed a half‐life 2.6 and 1.4 times higher than the soluble FTase and the FTase immobilized on PHB, respectively. The FTase immobilized on PHB and GLU‐PHB retained more than 40% and 55% of their initial activity after six sequential reaction batches, respectively. Both immobilized enzymes showed kinetic behaviors that were fitted by the Hill model, with transfructosylation activity maximum at concentrations between 400 g substrate L−1 and 500 g substrate L−1.CONCLUSIONThese results demonstrate that the FTase immobilized on PHB and, especially, on GLU‐PHB, are promising biocatalysts for FOS production in heterogeneous reaction systems. © 2022 Society of Chemical Industry (SCI).

Large-scale heterogeneous synthesis of monodisperse high performance colloidal CsPbBr3 nanocrystals

Colloidal lead halide perovskite nanocrystals (LHP NCs) are promising semiconductor materials for optoelectronic devices, but the high ionicity of LHP NCs makes their crystallization control and post-treatment difficult. Here, phosphonic acids (PAs) are employed as ligands to design a solid-liquid heterogeneous reaction system to regulate the LHP NC crystallization and achieve the desired focusing growth. During the heterogeneous synthesis, the precursors in the liquid phase are responsible for the burst nucleation and initial growth of NCs. Afterwards, the focusing growth of NCs is supported by the precursors released from the solid phase. In addition, the strong binding ability of PAs enables effective passivation of LHP NCs. Without post-treatment, gram-scale monodisperse CsPbBr3 NCs having photoluminescence with a full width at half-maximum of 18 nm and a quantum yield of near-unity are obtained. The CsPbBr3 NCs covered by a compact ligand layer keep initial quantum yield even after 18 cycles of purification, exhibiting excellent stability against polar solvents, ultraviolet irradiation and heat treatment. As scintillators, the prepared CsPbBr3 NCs show strong radioluminescence emission and high-resolution X-ray imaging.