Encapsulation Ni in HZSM-5 for catalytic hydropyrolysis of biomass to light aromatics
TL;DR: In this article, Ni-encapsulated (Ni@HZ5) and Ni-incorporated (xNi/HZ 5) zeolites were prepared via one-pot hydrothermal synthesis and impregnation method, respectively, and further employed for hydroconversion of pyrolytic volatiles of spent coffee grounds into benzene, toluene, ethylbenzene, xylene, naphthalene (BTEXN) in a drop tube reactor under H2 atmosphere.
About: This article is published in Fuel Processing Technology.The article was published on 2021-07-01. It has received 18 citations till now. The article focuses on the topics: Xylene & Ethylbenzene.
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TL;DR: In this article, temperature-programmed oxidation (TPO), Raman spectrometry, and X-ray photoelectron spectroscopy (XPS) are used to characterize coke species deposited on a 0.61% Pt/alumina catalyst for three reactions, carried out separately: partial oxidation (POX), steam reforming (SR), and autothermal reforming (ATR).
Abstract: Abstract Temperature-programmed oxidation (TPO), Raman spectrometry, and X-ray photoelectron spectroscopy (XPS) are used to characterize coke species deposited on a 0.61 wt% Pt/alumina catalyst for three reactions, carried out separately: partial oxidation (POX), steam reforming (SR), and autothermal reforming (ATR). Three individual compounds were used as simulants of liquid fuels in each of these three reactions: tetradecane, decalin, and 1-methylnaphthalene. The TPO profiles of the coke showed that partial oxidation and steam reforming resulted in generally greater coke deposition than autothermal reforming for each of the fuels. 1-Methylnaphthalene produces more coke than the other fuels in each of the reactions. Coke appears to be deposited both on the metal and the support, with the coke on the metal being more easily oxidized by TPO. Raman spectroscopy shows that there is no significant change in the carbon crystallite size on any of the catalysts; all are within the range of 1.45–1.83 nm. XPS analysis of carbon deposited during partial oxidation of tetradecane shows that small amounts of graphitic carbon (C/Al ratio
127 citations
TL;DR: The metal-in-zeolite composites as mentioned in this paper have experienced rapid development in heterogeneous catalysis, owing to the combination of the merits of both active metal sites and zeolite intrinsic properties.
Abstract: Zeolites with ordered microporous systems, distinct framework topologies, good spatial nanoconfinement effects, and superior (hydro)thermal stability are an ideal scaffold for planting diverse active metal species, including single sites, clusters, and nanoparticles in the framework and framework-associated sites and extra-framework positions, thus affording the metal-in-zeolite catalysts outstanding activity, unique shape selectivity, and enhanced stability and recyclability in the processes of Brønsted acid-, Lewis acid-, and extra-framework metal-catalyzed reactions. Especially, thanks to the advances in zeolite synthesis and characterization techniques in recent years, zeolite-confined extra-framework metal catalysts (denoted as metal@zeolite composites) have experienced rapid development in heterogeneous catalysis, owing to the combination of the merits of both active metal sites and zeolite intrinsic properties. In this review, we will present the recent developments of synthesis strategies for incorporating and tailoring of active metal sites in zeolites and advanced characterization techniques for identification of the location, distribution, and coordination environment of metal species in zeolites. Furthermore, the catalytic applications of metal-in-zeolite catalysts are demonstrated, with an emphasis on the metal@zeolite composites in hydrogenation, dehydrogenation, and oxidation reactions. Finally, we point out the current challenges and future perspectives on precise synthesis, atomic level identification, and practical application of the metal-in-zeolite catalyst system.
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TL;DR: In this article, the chemical composition, functional properties, and structural characteristics of these agro-industrial residues were evaluated in order to identify the characteristics that allow their reutilization in industrial processes.
Abstract: Spent coffee grounds (SCG) and coffee silverskin (CS) represent a great pollution hazard if discharged into the environment. Taking this fact into account, the purpose of this study was to evaluate the chemical composition, functional properties, and structural characteristics of these agro-industrial residues in order to identify the characteristics that allow their reutilization in industrial processes. According to the results, SCG and CS are both of lignocellulosic nature. Sugars polymerized to their cellulose and hemicellulose fractions correspond to 51.5 and 40.45 % w/w, respectively; however, the hemicellulose sugars and their composition significantly differ from one residue to another. SCG and CS particles differ in terms of morphology and crystallinity, but both materials have very low porosity and similar melting point. In terms of functional properties, SCG and CS present good water and oil holding capacities, emulsion activity and stability, and antioxidant potential, being therefore great candidates for use on food and pharmaceutical fields.
525 citations
489 citations
TL;DR: In this paper, an equilibrium, commercial diluted ZSM-5 catalyst was used as the base case, in comparison with a series of nickel (Ni) and cobalt (Co) modified variants at varying metal loading.
Abstract: The main objective of the present work was the study of different ZSM-5 catalytic formulations for the in situ upgrading of biomass pyrolysis vapors. An equilibrium, commercial diluted ZSM-5 catalyst was used as the base case, in comparison with a series of nickel (Ni) and cobalt (Co) modified variants at varying metal loading (1–10 wt.%). The product yields and the composition of the produced bio-oil were significantly affected by the use of all ZSM-5 catalytic materials, compared to the non-catalytic flash pyrolysis, producing less bio-oil but of better quality. Incorporation of transition metals (Ni or Co) in the commercial equilibrium/diluted ZSM-5 catalyst had an additional effect on the performance of the parent ZSM-5 catalyst, with respect to product yields and bio-oil composition, with the NiO modified catalysts being more reactive towards decreasing the organic phase and increasing the gaseous products, compared to the Co 3 O 4 supported catalysts. However, all the metal-modified catalysts exhibited limited reactivity towards water production, while simultaneously enhancing the production of aromatics and phenols. An interesting observation was the in situ reduction of the supported metal oxides during the pyrolysis reaction that eventually led to the formation of metallic Ni and Co species on the catalysts after reaction, which was verified by detailed XRD and HRTEM analysis of the used catalysts. The Co 3 O 4 supported ZSM-5 catalysts exhibited also a promising performance in lowering the oxygen content of the organic phase of bio-oil.
446 citations
TL;DR: This review provides a comprehensive summary of the recent progress in the synthesis and catalytic properties of the encapsulated metal nanoparticles, including their encapsulation in nanoshells of inorganic oxides and carbon, porous materials, and organic capsules.
Abstract: Metal nanoparticles have drawn great attention in heterogeneous catalysis One challenge is that they are easily deactivated by migration-coalescence during the catalysis process because of their high surface energy With the rapid development of nanoscience, encapsulating metal nanoparticles in nanoshells or nanopores becomes one of the most promising strategies to overcome the stability issue of the metal nanoparticles Besides, the activity and selectivity could be simultaneously enhanced by taking advantage of the synergy between the metal nanoparticles and the encapsulating materials as well as the molecular sieving property of the encapsulating materials In this review, we provide a comprehensive summary of the recent progress in the synthesis and catalytic properties of the encapsulated metal nanoparticles This review begins with an introduction to the synthetic strategies for encapsulating metal nanoparticles with different architectures developed to date, including their encapsulation in nanoshells of inorganic oxides and carbon, porous materials (zeolites, metal-organic frameworks, and covalent organic frameworks), and organic capsules (dendrimers and organic cages) The advantages of the encapsulated metal nanoparticles are then discussed, such as enhanced stability and recyclability, improved selectivity, strong metal-support interactions, and the capability of enabling tandem catalysis, followed by the introduction of some representative applications of the encapsulated metal nanoparticles in thermo-, photo-, and electrocatalysis At the end of this review, we discuss the remaining challenges associated with the encapsulated metal nanoparticles and provide our perspectives on the future development of the field
343 citations
TL;DR: Zeolites can be used as ion-exchange reagents to remove Ca and Mg ions from ‘‘hard’’ water and the second largest application is catalysis, with Fluid Catalytic Cracking and Hydro-Cracking as the leading commercial processes in the oil refinery industry.
Abstract: Zeolites are crystalline microporous aluminosilicates, which are built up from corner-sharing SiO4and AlO4-tetrahedra. These porous materials are formed in nature in association with volcanic activity, but can also be synthesized in the laboratory. Currently, there are 229 different zeolite structures known, not necessarily composed of SiO4and AlO4tetrahedra as many elements from the periodic table can now be an integral part of zeolite framework structures. Interestingly, theory has predicted that millions of other zeolite structures can be constructed from the primary building blocks of zeolites, illustrating the enormous potential of this research area for designing new functional porous materials. The Swedish chemist Axel Cronstedt was the first to describe zeolites in 1756. He noted that the mineral stilbite appeared to boil when heated. Cronstedt therefore named these materials zeolites or ‘‘boiling stones’’ (from Greek z eo – to boil and l iyoB – stone). Zeolites are used in large quantities in a variety of commercial processes. The largest zeolite application is certainly detergency. Zeolites can be used as ion-exchange reagents to remove Ca and Mg ions from ‘‘hard’’ water. The second largest application is catalysis, with Fluid Catalytic Cracking (FCC) and Hydro-Cracking (HC) as the leading commercial processes in the oil refinery industry. Other uses include adsorbents, as well as various uses of natural zeolites, a Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. E-mail: B.M.Weckhuysen@uu.nl b State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China. E-mail: jihong@jlu.edu.cn
305 citations