Polypropylene (PP) shows potential applications in high-tech fields, such as energy storage and medical devices. However, the residual catalyst system and the oligomers of propylene restrict their practical application. Here, comprehensive analysis of the extracts from the as-polymerized PP granules with different solvent systems was conducted, for achieving the ultraclean PP. The results indicated that the efficient extraction of the residual catalyst system and the oligomers of propylene could be achieved with n-hexane as solvent. The results could be used to explore the transition and migration of Z-N catalyst system in propylene polymerization, moreover, the proposed post-polymerization extraction strategy showed promising potential to produce ultraclean PP for hi-tech applications.

Two widely used classes of so-called "reinforcing nucleating agents (NAs)", namely phosphates and carboxylates, are extensively applied in the polypropylene (PP) field. Although both can markedly accelerate crystallization and enhance stiffness, their reinforcing performances are reported to be different. To understand the origin of this difference, the effects of representative NAs from two types, phosphate-based NA11 and carboxylate-based calcium hexahydrophthalate (CaHHPA) at 0.2 wt%, on the nucleation and crystal growth behaviors of PP were investigated. Comparative studies on nucleation show that although CaHHPA is more effective in reducing the interfacial free energy difference and NA11 provides more nucleation sites, both NAs collectively lead to a comparable and significant increase in the nucleation density (e.g., from 2.0 & times; 108 m(-3) for neat PP to 3.3 & times; 1011 for NA11-containing and 4.5 & times; 1011 m(-3) for CaHHPA-containing samples at 140 degrees C). Regarding crystal growth, kinetic analysis reveals that both NAs exert little influence on growth dimensionality, while characterization of the crystalline structure under relatively weak flow demonstrates distinct epitaxial growth modes: For NA11, PP attaches onto the (001) lateral surfaces with the chain axis aligning along the b-axis of NA11. For CaHHPA, PP attaches onto the top and bottom surfaces with the chain axis aligning along the rows of adjacent cyclohexane rings. Based on the fact that the oriented crystalline structure under flow precisely corresponds to the reported anisotropic reinforcing performance, our results suggest that the divergent performance between phosphate-and carboxylate-based NAs could relate to differences in the crystal growth modes.

Lignin derivatives are considered a renewable resource and their efficient utilization and clean conversion have attracted increasing research attention. However, construction of efficient catalytic system for large-scale transformation of lignin derivatives to production value-added fine chemicals under mild reaction conditions remains a significant challenge. Herein, a Ga2O3-supported bimetallic catalyst was developed, by incorporating cobalt into Ga2O3 and depositing nickel onto its surface, the Co5Ni5/Ga2O3 catalyst was successfully constructed, which resulted in the formation of abundant oxygen vacancies and enabled hydrogen spillover on the non-reducible Ga2O3 support. This modification endowed Co5Ni5/Ga2O3 catalyst with hydrogenation capability and significantly enhanced its catalytic activity. The hydrodeoxygenation of guaiacol achieved a cyclohexanol yield of up to 95.1% under mild reaction condition of 180 degrees C, 1.2 MPa as compared with noble metal-based catalysts. Mechanism study confirmed that nickel facilitates homolytic hydrogen cleavage, while cobalt doping enhances guaiacol adsorption and the energy barrier for hydrogen transfer decreased from 0.52 to 0.24 eV, which confirm the efficient hydrodeoxygenation of guaiacol. This study provides a novel strategy for enhancing hydrogen spillover for catalyst design in the hydrodeoxygenation of guaiacol.

Antioxidants and acid scavengers are fundamental additives for Ziegler-Natta (ZN) polyolefins. Although zinc stearate (ZnSt2) and calcium stearate (CaSt2) are widely used with conventional synthetic antioxidants, their applicability to the natural antioxidant vitamin E (VE) remains unclear. Here, the effects of ZnSt2 and CaSt2 on the processing stabilization efficiency of VE in a ZN polyethylene (ZN-PE) were investigated over a broad loading range of 50–2000 ppm. At low loading (e.g., 250 ppm), ZnSt2 improved the stabilization efficiency of VE, as evidenced by higher melt oxidative stability and better retention of melt viscosity, molecular weight, and chemical structure during repeated extrusion, whereas CaSt2 weakened VE stabilization. At high stearate loading (e.g., 2000 ppm), both stearates impaired the stabilization efficiency of VE, as reflected by lower melt oxidative stability, poorer retention of melt viscosity and molecular weight, and accelerated formation of degradation-related structures during repeated extrusion. Based on these results and the squalane model tests, we hypothesize that both stearates intrinsically weaken VE stabilization, whereas only ZnSt2 may partially protect VE by mitigating the more pronounced negative effect of catalyst residues. This balance may account for the beneficial effect of low-loading ZnSt2, the detrimental effect of excessive ZnSt2, and the consistently adverse effect of CaSt2 in the studied ZN-PE with low catalyst residue levels.

Residual catalysts in Ziegler-Natta (ZN) polyolefins usually significantly impair the effectiveness of antioxidants and the incorporation of acid scavengers is an effective method to mitigate these detrimental effects. With the increasing use of natural antioxidants like vitamin E (VE) in human-safety applications, whether their stabilizing effectiveness is affected by catalyst residues and whether traditional acid scavengers remain effective have become key issues requiring urgent resolution. This study systematically investigated the impact of hydrotalcite, a conventional acid scavenger, on VE's thermal stabilization performance in ZN polyethylene (ZN-PE). The results demonstrated that combining 500 ppm VE with 500 ppm hydrotalcite significantly extended the oxidation induction time of ZN-PE to 55.7 min at 190 degrees C, which surpassed the 30.7 min achieved by 1000 ppm VE alone. The changes in chemical structure, mechanical properties, and color of different samples after multiple extrusions and accelerated aging further confirmed the strong synergistic effect of VE and hydrotalcite in enhancing the thermal-oxidative stability of ZN-PE. Mechanistic investigations revealed that hydrotalcite primarily functioned by eliminating the impairment of VE's antioxidant efficiency caused by the ZN catalyst. Additionally, hydrotalcite exhibited a certain adsorption effect on VE, which could control the release of VE, thereby extending its antioxidant efficiency in ZN-PE. These findings highlight the critical role of acid scavengers in optimizing VE performance, providing an effective strategy to optimize the use of natural antioxidants in ZN polyolefin stabilization.

Polypropylene (PP) shows potential application in energy and biomedical fields. However, the residue of the Z-N catalyst system limits its practical application. Here, the transition and migration of the Z-N catalyst system in propylene polymerization were explored by the comprehensive analysis of the extract from as-synthesized polypropylene granules with isopropyl alcohol/n-hexane. The results indicated that the catalyst support (MgCl2) and co-catalyst (triethylaluminium) could not be extracted, while the Ti-based active species could be partially removed with decreased Ti content of 0.07 ppm from 0.26 ppm in the as-synthesized polypropylene granules. Moreover, the electron donors and oligomers of propylene with a relative number-averaged molecular weight (Mn) of 5.4 x 103 with a PDI of 4.43 could be removed. The ultra-clean PP could be obtained via the proposed strategy for hi-tech applications, with lower contents of polar and odorous small molecules and oligomers.

Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials. In this study, four linear low-density polyethylenes (LLDPEs) with comparable molecular weights but different short-chain branch (SCB) contents (ranging of 5–66 per 1000 carbon atoms) were modified via dynamic melt mixing using 2 wt

ABSTRACT Polypropylene (PP) membranes show promising applications in electric and biomedical fields. However, the residue of the Z–N catalyst system would decline their electrical properties, limiting their practical applications. To explore the transition and migration of the Z–N catalyst system in propylene polymerization, the as‐synthesized PP granules are extracted with polar solvent (ethanol) and nonpolar solvent ( n ‐hexane) respectively. The extracts are quantitatively analyzed with 1 H NMR technique. The results demonstrate that the donors in the Z–N catalyst system and the low‐molecular‐weight oligomers of propylene could be removed with both solvents, while the metal‐containing species could only be extracted with ethanol after deactivation. A secondary extraction is proposed to open a new idea for the manufacturing of ultra‐clean PP for specific high‐technology applications.

The efficient catalytic conversion of the biomass platform molecule furfural into biofuels or other high-valueadded chemicals is currently a research hotspot. However, the hydrogenation of furfural possesses challenges due to the occurrence of multiple side reactions that generate various by-products. Herein, S-doped mesoporous carbon spheres (CS-S) with an ordered and accessible structure were precisely designed and synthesized. Subsequently, similar to 1.8 nm Pd nanoclusters were immobilized within the radial mesoporous structure of CS-S to obtain a Pd/CS-S catalyst. This catalyst was used for the hydrogenation of furfural and acetophenone into tetrahydrofurfuryl alcohol (THFA) and 1-phenylethanol, respectively, and 99 % conversion and more than 90 % selectivity were achieved. Mechanistic study revealed that the electron-deficient Pd nanoclusters anchored on CS-S exhibit higher adsorption energies for reactant molecules, thus facilitating the pre-adsorption and activation of substrate molecules. Moreover, the Gibbs free energy for each step of the hydrogenation process is lower on the electron-deficient Pd metal surface, leading to excellent catalytic hydrogenation performance. In addition, the Pd/CS-S catalyst also exhibited remarkable recyclability and stability over multiple reaction cycles. This work facilitates the construction of stable metal nanocluster-based catalysts for enabling highly selective catalytic hydrogenation.

For Zieglar-Natta (Z-N) polypropylene (PP) to which a nucleating agent (NA) was added to regulate the properties, selecting an appropriate acid scavenger, a necessary additive for Z-N PP, is important for optimizing the effectiveness of the NA. However, the impact of various acid scavengers on the performance of NAs has not been systematically studied. In this work, the effect of two most widely used acid scavengers, calcium stearate (CaSt2) and zinc stearate (ZnSt2), on PP crystallization promotion performance of a commonly used NAs, NX8000 (a typical representative of sorbitol-type NAs family) was systematically investigated. It was found that CaSt2 did not significantly alter the crystallization temperature (T c) of PP containing NX8000, while ZnSt2 was detrimental to the nucleation benefit of NX8000, especially in the NA concentration range, where effective nucleation began but remained below the "critical saturation concentration". The mechanism study showed that CaSt2 added to PP almost remains chemically unchanged during heating and exhibits no significant impact on the NA. Differently, ZnSt2 undergoes chemical reactions in a matrix at elevated temperature, producing stearic anhydride, which reacts with NX8000. As a result, a portion of the NA is consumed, leading to a reduction in its efficacy. Our work not only contributes to a comprehensive understanding of mechanisms when multiple additives are used simultaneously but also helps optimize additive formulations to maximize the performance of each component.

The semi-hydrogenation of alkynols to produce high-value enols is a critical transformation in the fine chemicals industry, yet achieving high selectivity while avoiding over-hydrogenation remains a formidable challenge for Pd-based catalysts. Herein, we present the synthesis of Pd nanoclusters anchored on N-doped porous carbon spheres (Pd/N-PCS) through a co-self-assembly approach combined with a small-molecule-assisted strategy. The mesoporous Pd/N-PCS catalyst, featuring abundant pyridinic-N and pyrrolic-N species, precisely modulates the electronic properties of active Pd sites. Under mild conditions, Pd/N-PCS achieves exceptional performance with 99 % conversion and selectivity in alkynol semi-hydrogenation, outperforming most reported Pd-based catalysts. Mechanistic investigations demonstrate that N-site coordination fine-tunes the electronic states of Pd nanoclusters, resulting in weak adsorption of enol products and effectively suppressing their over-hydrogenation. Moreover, Pd/N-PCS exhibits remarkable versatility in the semi-hydrogenation of diverse alkynols and maintains robust catalytic activity across multiple cycles. This study not only advances the design of efficient metalnanocluster catalysts but also establishes a practical route for the selective synthesis of high-value enols, offering significant potential for industrial applications.

Introducing component-selective polymer chains onto the surface of a particle is an effective approach to improve the compatibilization efficiency of a particle-based compatibilizer. In this study, two particles with different kinds of component-selective polymer chains that have the same length and similar density but different graft locations were synthesized and their compatibilization effects were comparatively investigated. It was found that compared with the particle with homogeneous PMMA and PP grafts (R-P), the particle with a hemisphere of poly(methyl methacrylate) (PMMA) grafts and other hemisphere of polypropylene (PP) chains (J-P) showed a better compatibilization effect under equal loadings, although both particles exhibited high efficiency. The better compatibilization effect of particles with Janus grafts may be attributed to the stronger entanglements between grafted polymer chains and selective individual components. This work suggests that optimizing the graft location of a particle is an effective strategy for improving its compatibilization efficiency and helpful for the design of advanced particle compatibilizers.

Although Ziegler-Natta (Z-N) polyolefins have been widely used as raw materials to produce pharmaceutical or food packaging, the migration of acid scavengers, an additive usually introduced in Z-N polyolefins, from the packaging to its contents has not been reported. In this work, the migration of the two most used acid scavengers, calcium stearate (CaSt2) and zinc stearate (ZnSt2), from a Z-N polypropylene random copolymer (PPR) into water during autoclaving at 121 °C were comparatively investigated. It was found that, for PPR plates containing 0.1 wt

Atomic-level modulation of covalent organic frameworks (COFs) structure for enhanced photocatalytic oxidation is highly important but still challenging. Herein, a series of beta-ketoenamine-linked COFs have been synthesized by using 2,4,6-triformyl-phloroglucinol (Tp) as a modular molecule, 5,5 '-Diamino-2,2 '-bipyridine (Bpy), and 3,6-Pyridazinediamine (Dz) linkers with atomic level N sites substitute 4,4 '-diamino-bipheny (BD) and 1,4-phenylenediamine (Pa) to construct COFs with adjustable photocatalytic performance. Mechanism study reveals that in COFs with N sites-based linkers, O-1(2) adsorbed on the pore walls of TpBpy-COF (-4.23 kcal mol(-1)) and TpDz-COF (-4.63 kcal mol(-1)) with higher adsorption energy than on TpBD-COF (-2.73 kcal mol(-1)) and TpPa-COF (-2.17 kcal mol(-1)), enabling O-1(2) activation and high catalytic performance toward thioether oxidation with almost >99% conversion, outperforming most reported organic photocatalysts. Notably, TpBpy-COF exhibits a superior catalytic activity for thioether oxidation (e.g., aromatic thioethers, aliphatic sulfide, and Mustard Gas sulfide) because of its narrow bandgap, fast charge separation and transfer ability, and single-ended activation ability. This study provides a novel and effective strategy for modulating exciton effects and photocatalytic activity of COFs-based organic photocatalysts at the atomic level.

The controlled fabrication of metal nanocluster-based catalysts with high catalytic performance and stability is currently a research hotspot, while it is still a research challenge. Herein, nitrogen-doped mesoporous carbon spheres (CS-N) with a regular and open structure were precisely designed and prepared. Pd nanoclusters with an average size of 1.44 nm were highly dispersed and stably confined in the radial mesoporous structure of CS-N, forming Pd/CS-N catalysts. The obtained Pd/CS-N catalysts showed high catalytic performance in the hydrogenation of phenol to cyclohexanone and hydrogenation of benzoic acid to cyclohexanecarboxylic acid (yield of almost 99%) under mild reaction conditions, outperforming most reported Pd nanoparticle-based catalysts. Theoretical calculation illustrates that the Pd nanocluster exists as an electron-deficient state on Pd/CS-N, thus can efficiently facilitate reactant preadsorption and activation, and also reduce the Gibbs free energy of the rate-determining step of the hydrogenation reactions. Moreover, the Pd/CS-N catalyst exhibited good reusability and stability. Thus, this work will promote the precise construction of stable metal nanocluster-based catalysts, enabling highly efficient catalytic hydrogenation reactions.

In industry, crosslinked polyethylene (XLPE) cable insulation is usually produced from crosslinkable compounds consisting of low-density polyethylene (LDPE) and additives, which known as "cable materials". Considering that in addition to additives, the structure of matrix resin is a key factor in determining the property of XLPE, it is worthy to study the structure requirements of matrix resin for the development of cable materials with different voltage grades. In this work, the structure of matrix resins of a high voltage grade and an extra high voltage grade cable material were comparatively investigated. Interestingly, it was found that the matrix resins have no significant difference in chain structure parameters including molecular weight and its distribution and vinyl content between two samples, and their crystalline structure as well as the melt rheology and melting crystallization behavior are also very similar. These results suggest that these matrix resins may not substantially differ. Our work shows that cable materials with different voltage grades are not necessarily diverge in terms of matrix resin structure, and it could be possible to develop higher grade cable materials using the same matrix resin as lower grade counterparts.

The mechanical strength of polylactic acid (PLA) can be improved by carbon fiber (CF) compositing to expand its application in tissue engineering scaffolds. However, the mechanical strength of CF-reinforced polylactic acid (CFRPLA) composites is compromised due to weak interfacial interaction resulting from the chemically inert surface of CF. In the article, carbon nanotube (CNT) with poly(diallyldimethylammonium chloride) (PDDA) as a coupling agent was covered on CF to improve the chemical activity and roughness of the surface of CF, and then the as-prepared CF-PCNT were further incorporated into PLA via melt compounding. The yield strength, modulus, and thermal conductivity of PLA/CF-PCNT were 14.09%, 7.65%, and 5.24% higher than those of PLA/CF, respectively, and the volume resistivity was 99.74% lower at a 10 wt% loading. The enhancement for the mechanical properties of PLA/CF-PCNT composites could be ascribed to the mechanical locking, hydrogen bonds and covalent bonds between CF and matrix through the interface modulation of CNT and PDDA. This facile and non-destructive method offers a novel strategy for the modification of CF fillers.Highlights CF was modified by PDDA and CNT through a facile and non-destructive method. The active functional groups and roughness on the surface of CF were increased. The surfaces of CFs were characterized by FT-IR, Raman spectra, XPS and SEM. The interface was improved by mechanical locking, covalent, and hydrogen bonds. The mechanical strength, electrical and thermal conductivity of composites were improved.

Using an ideal trimethylbenzene mix-ture system as a model in the isomerization of 1,2,4-trimethylbenzene to 1,3,5-trimethylbenzene,the thermodynamic equilibrium composition of mixed trimethylbenzene at different temperatures and the conversion rate of 1,2,4-trimethylbenzene,the se-lectivity and yield of 1,3,5-trimethylbenzene within the reaction temperature range were obtained through the thermodynamic calculations.The isomerization reaction was carried out by HZSM-5 catalyst modi-fied with Ag and its performance for the isomerization was evaluated in a pressurized fixed bed reactor.The process conditions of reaction temperature,reaction pressure,mass space velocity,and Ag addition mass fraction were optimized.The results showed that n(1,2,3-trimethylbenzene)∶n(1,2,4-trimethyl-benzene)∶n(1,3,5-trimethylbenzene)was 0.052∶0.674∶0.274 in the average thermodynamic equilibri-um composition of mixed trimethylbenzene.The con-version rate of 1,2,4-trimethylbenzene was 32.6%,the selectivity and yield of 1,3,5-trimethylbenzene were 75.6%and 27.4%respectively within the reac-tion temperature range.The conversion rate of 1,2,4-trimethylbenzene was 33.80%,and the selec-tivity of 1,3,5-trimethylbenzene was 71.34%,and the highest one-way yield of 1,3,5-trimethylben-zene could reach 24.90%under the optimized condi-tions of the reaction temperature at 280℃,the reac-tion pressure at 1.6 MPa,and the mass space velocity at 1.0 h-1,Ag addition mass fraction at 1%,and the molar ratio of hydrogen to oil at 5.

运用基于风险的检验技术(RBI)和ORBITONSHORE软件对原油稳定装置进行了风险评估和风险排序，阐述了原油稳定装置各单元的腐蚀机理、破坏形式和腐蚀速率，提出了降低风险等级的有效措施。

通过工艺流程模拟,并根据管材专用耐热聚乙烯(PE-RT)的要求,开发了管材专用茂金属PE-RT mPE3010.确定了mPE3010的聚合工艺参数和产品技术质量指标,实现了对原料杂质含量、乙烯用量、反应器床高、干粉催化剂注入和反应器块料等生产难点的控制.结果表明:mPE3010的熔体流动速率为1.89 g/10 min,密度为0.9364 g/cm3,弯曲模量为561.94 MPa,熔点为127.8℃,具有良好的耐热性能、优良的力学性能和加工性能.