Towards rational design of core–shell catalytic nanoreactor with high performance catalytic hydrogenation of levulinic acid

Banerjee, Biplab; Singuru, Ramana; Kundu, Sudipta; Dhanalaxmi, Karnekanti; Bai, Linyi; Zhao, Yanli; Reddy, Benjaram M.; Bhaumik, Asim; Mondal, John

doi:10.1039/c6cy00169f

Cited by 50 publications

(26 citation statements)

References 61 publications

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“…Compared with the homogenous analogues, including complexes bis‐NHC‐Ir 4a , bis‐NHC‐Pd 5 , and NHC‐Ru 6 , POMP‐NHC‐Ir 1d , POMP‐NHC‐Pd 2 , and POMP‐NHC‐Ru 3 exhibited much higher catalytic activities under otherwise identical reaction conditions (17% vs 99%, 18% vs 82%, and 56% vs 81%, Figure a). It has to be pointed out, there are few reports on Pd‐catalyzed hydrogenation of LA to GVL under hydrogen atmosphere, and good result and enhanced catalytic activity could be achieved by POMP‐NHC‐Pd 2 even at 130 ppm catalyst loadings. Furthermore, other privileged and commercially available catalysts ( 10‐12 ) were also employed in this transformation, only trace to inferior yields were obtained under optimal reaction conditions (Figure a).…”

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

et al. 2019

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supported catalysts by simply knitting rigid aromatic ligands via hypercross-linking (Friedel-Crafts reactions) has recently been proposed. [13] After further postmodification/activation, several MCPPs have been successfully developed. [14][15][16][17] However, with postmodification, avoiding the problems, like low density of catalytic sites due to incomplete modification and random/ nonselective metal anchoring, can be difficult. These issues may still lead to low catalytic activity and selectivity, especially in some challenging transformations. [18] In light of N-heterocyclic carbene-metal (NHC-M) complexes can act as robust and viable catalysts in a broad range of reactions, [19][20][21][22][23][24][25][26][27][28] various strategies have been developed for their immobilization. [29,30] Among them, selfsupporting strategy may represent one of the most practical and efficient approaches. [31][32][33][34] It has to be noted that NHC ligands still have to be carefully designed and modified before selfsupporting. Alternatively, the high catalytic activities and robustness of NHC-M complexes make them perfect candidates for direct knitting. To the best of our knowledge, there are only two reported examples on MCPPs in which the NHC ligands are firstly knitted and then coordinated to active metal ions (postmodification approach). [14,15] Direct knitting of NHC-M complexes to fabricate porous organometallic polymers (POMPs) that do not require postmodification/activation is still unknown.Herein, we have designed and prepared a series of unprecedented porous organometallic polymers POMPs-NHC-M 1-3 via direct knitting three types of bis-chelating NHC-M complexes (M = Ir, Pd, and Ru, Figure 1a). Using this facile strategy, which does not require postmodification/activation, 1) the metal active sites are atomically dispersed in the hierarchical porous matrix, and 2) the intrinsic well-defined bis-chelating mode and their molecular catalytic properties are maximally retained, which allows 3) the precise design and control of the immobilized catalysts at the molecular level. The advantages of direct knitting allow the resulting POMPs-NHC-M 1-3 to behave as recyclable solid single-site catalysts and exhibit extremely high catalytic activities in both hydrogenation and dehydrogenation reactions.In light of their robustness toward Friedel-Crafts reaction conditions, bis-chelating NHC-M (Ir, Pd and Ru) complexes 4, 5 and 6, derived from corresponding benzimidazolium salts, [24,25,27] were selected to fabricate POMPs via direct knitting with benzene ( Figure 1a). Concerning the plausible impact Porous organometallic polymers (POMPs) with hierarchical pore structures, high specific surface areas, and atomically dispersed metal (Ir, Pd, Ru) centers are successfully fabricated by a facile one-pot method through direct knitting of diverse N-heterocyclic carbene metal (NHC-M) complexes. These polymers can function as recyclable solid single-site catalysts and exhibit excellent catalytic activity and selectivity in both dehydrogenat...

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Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

et al. 2019

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“…However, the GVL selectivity decreased dramatically from 95 % to 64 % upon raising the temperature further to 150 °C (Table , entries 16–18). Coke deposition, caused by some unexpected adverse reactions such as over‐hydrogenation or hydrogenolysis, was responsible for this reduced GVL selectivity (Figure ) …”

Section: Catalytic Conditionsmentioning

confidence: 99%

“…The GVL selectivity of Pd@C decreased markedly from 95 % to 70 % upon raising the temperature from 100 °C to 120 °C, and a similar decrease in GVL selectivity (from 95 % to 64 %) under the action of Pd@SiO 2 was also observed upon increasing the temperature from 120 °C to 150 °C. These results were attributed to the coverage of active sites by coke deposits on the catalyst surface …”

Section: Stability Of Catalystsmentioning

confidence: 99%

Heterogeneous Catalytic Hydrogenation of Levulinic Acid to γ‐Valerolactone with Formic Acid as Internal Hydrogen Source

Lü

Xiong

et al. 2020

ChemSusChem

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As one of the most promising biomass‐based platform molecules, γ‐valerolactone (GVL) can be synthesized from a variety of lignocellulosic feedstocks through different hydrogen supply pathways. Among these transformation routes, the hydrogenation of levulinic acid (LA) to GVL by using formic acid (FA) as the internal hydrogen source is regarded as a critical path for the sustainable development of renewable energy systems. Although a large number of studies on the synthesis of GVL have been reported, the FA/LA catalytic system has not been interpreted as thoroughly as it should be. In this Minireview, core concerns are focused on key issues and their effects in this FA/LA catalytic system. The catalytic mechanism, together with competitive adsorption behavior between FA and LA on heterogeneous catalysts, is presented. The effects of active metal species and catalyst supports on the overall catalytic performance are summarized, and the influences of key condition parameters, including the time, temperature, FA/LA molar ratios, and aqueous solvent, are discussed. In particular, impacts and improvements of coke deposition and metal leaching, which could greatly affect the catalyst stability, are analyzed in detail. Additionally, several feasible suggestions for the enhancement of the catalytic efficiency and stability are also proposed.

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“…However, the as‐prepared catalysts in this work showed dramatic differences in stability; the optimal Ru/ZSM‐5C (commercial support by wet impregnation) can still achieve 95 % conversion at the 10th cycle (conv. >95 %, yield >85 %), which is as stable as the latest core–shell silica‐based nanocatalyst (used for 10 runs) . However, Ru/ZSM‐5S (supercritical CO 2 ‐assisted homogeneous deposition in commercial support) deactivated sharply at the 4th cycle, with its conversion rate dropped to 25 %, and similar deactivation also took place in Ru/ZSM‐5M (mesoporous support by wet impregnation).…”

Section: Introductionmentioning

confidence: 98%

A Robust Ru/ZSM‐5 Hydrogenation Catalyst: Insights into the Resistances to Ruthenium Aggregation and Carbon Deposition

Zhang

et al. 2017

ChemCatChem

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A long‐life topic in the field of heterogeneous catalysis has been to develop supported catalysts that are stable against the aggregation of active metal and carbon deposition. Herein, we report a highly stable Ru/ZSM‐5 catalyst for the hydrogenation of levulinic acid in water, which can be recycled at least 10 times without apparent loss of activity (conv. >95 %, yield >85 %). The influences of types of Al species, structure of support, Ru sizes, Ru leaching, and carbon deposition, etc. on activity and stability were discussed in detail. It was confirmed that the tetrahedral‐coordinated framework Al in ZSM‐5 contributed to the favorable metal–support interaction, and thus suppressed the aggregation and leaching of ruthenium during recycling. Besides, the suitable pore volume and channel network connectivity successfully prevent from deposition of carbonaceous residues.

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Towards rational design of core–shell catalytic nanoreactor with high performance catalytic hydrogenation of levulinic acid

Abstract: Core–shell catalytic nanoreactor was designed, exhibiting high catalytic activity for levulinic acid hydrogenation.

Cited by 50 publications

References 61 publications

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

Heterogeneous Catalytic Hydrogenation of Levulinic Acid to γ‐Valerolactone with Formic Acid as Internal Hydrogen Source

A Robust Ru/ZSM‐5 Hydrogenation Catalyst: Insights into the Resistances to Ruthenium Aggregation and Carbon Deposition

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