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27 pages, 6045 KB

Open AccessReview

Zirconium-Containing Metal–Organic Frameworks (MOFs) as Catalysts for Biomass Conversion

by Anastasia Rapeyko and Francesc X. Llabrés i Xamena

Appl. Sci. 2025, 15(5), 2609; https://doi.org/10.3390/app15052609 - 28 Feb 2025

Cited by 1 | Viewed by 2383

In this work, we review some illustrative examples to evidence the potential of two archetypal Zr-containing MOFs, UiO-66 and MOF-808, as heterogeneous catalysts for converting biomass-derived products into valuable chemicals. The reactions are organized in three blocks, depending on the biomass source: carbohydrates, lipids, and other sources. Through this review, we will show that the chemical properties of these two Zr-MOFs are significantly different in terms of the nature and strength of acid sites, which largely depends on the number of missing linker defects of the solid and its hydration state. While hydrated UiO-66 bears relatively strong Brønsted-induced acid sites, dehydrated MOF-808 is more than competent as a Lewis acid catalyst. Therefore, we will pick one or the other catalyst depending on the particular demands of the catalytic transformation that we want to carry out. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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15 pages, 3497 KB

Open AccessArticle

Larix Sibirica Arabinogalactan Hydrolysis over Zr-SBA-15; Depolymerization Insight

by Valentin V. Sychev, Yuriy N. Malyar, Andrey M. Skripnikov, Yuriy A. Trotsky, Yulia N. Zaitseva, Anna O. Eremina, Valentina S. Borovkova and Oxana P. Taran

Molecules 2022, 27(24), 8756; https://doi.org/10.3390/molecules27248756 - 9 Dec 2022

Cited by 5 | Viewed by 2282

Abstract

Arabinogalactan depolymerization over solid Zr-containing SBA-15-based catalyst was studied via HPLC, GPC, and theoretical modeling. Arabinogalactans (AG) are hemicelluloses mainly present in larch wood species, which can be extracted on an industrial scale. The application of solid acid catalysts in the processes of hemicellulose conversion can exclude serious drawbacks such as equipment corrosion, etc. Characterization of 5%Zr-SBA-15 confirmed the successful formation of the mesoporous structure inherent to SBA-15 with fine Zr distribution and strong acidic properties (XRD, XPS, FTIR, pH_pzc). Carrying out the process at 130 °C allowed us to achieve total products yield of up to 59 wt%, which is represented mainly by galactose (51 wt%) and minor (less than 9 wt%) presence of arabinose, furfural, 5-HMF, and levulinic acid. The temperature increases up to 150 °C resulted in a total product yield drop down to 37 wt%, making temperature elevation above 130 °C obsolete. According to the theoretical investigations, arabinogalactan depolymerization follows the primary cleavage of the β(1→3) bonds between the D-galactose units of the main chain, which is also confirmed by GPC. Full article

(This article belongs to the Special Issue Recent Insights into Biopolymer Processing, from Preparation to Fundamental Properties and Industrial Applications)

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10 pages, 2030 KB

Open AccessCommunication

An Efficient Zr-ZSM-5-st Solid Acid Catalyst for the Polyol Esterification Reaction

by Huaigang Su, Ze Zong, Wenjing Lou, Qin Zhao, Xiaobo Wang, Xiang Feng, Yanxing Qi and Zhaoning Song

Catalysts 2022, 12(8), 901; https://doi.org/10.3390/catal12080901 - 16 Aug 2022

Cited by 2 | Viewed by 2990

Abstract

In this study, Zr active species were implanted into a ZSM-5 zeolite framework to form a solid acid catalyst through steam treatment and the liquid-solid isomorphous substitution process. The as-synthesized Zr-ZSM-5-st catalyst ensured excellent esterification of trimethylolpropane and fatty acids (FAs) to achieve a polyol ester production yield of 94.41%. Combined with N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, transmission electron microscopy mapping, X-ray photoelectron spectroscopy, NH₃ temperature-programmed desorption, and inductively coupled mass plasma spectroscopy were conducted. The results revealed that the excellent performance of Zr-ZSM-5-st catalyst could be attributed to the enhanced acidity and the developed surface area and pore structure. Full article

(This article belongs to the Topic Green and Sustainable Chemistry)

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13 pages, 5525 KB

Open AccessArticle

CeO₂-ZrO₂ Solid Solution Catalyzed and Moderate Acidic–Basic Sites Dominated Cycloaddition of CO₂ with Epoxides: Halogen-Free Synthesis of Cyclic Carbonates

by Jie Gao, Chengguang Yue, Hao Wang, Jiaxin Li, He Yao, Mei-Yan Wang and Xinbin Ma

Catalysts 2022, 12(6), 632; https://doi.org/10.3390/catal12060632 - 9 Jun 2022

Cited by 20 | Viewed by 3657

Abstract

For the production of cyclic carbonates from the cycloaddition of CO₂ with epoxides, halogen pollution and product purity are two of the most common problems due to the usage of homogeneous halogen-containing catalysts such as ammonium salt and alkali metal halide. Hence, the development of a novel, halogen-free and efficient catalyst for the synthesis of high-purity cyclic carbonates is significant. Here, a series of acid–base bifunctional Ce_1-xZr_xO₂ nanorods were successfully prepared. The Ce_1-xZr_xO₂ nanorods could catalyze the cycloaddition of CO₂ with epoxides efficiently without any halogen addition. Especially for the Ce_0.7Zr_0.3O₂ catalyst, a conversion of 96% with 100% 1,2-butylene carbonate selectivity was achieved. The excellent catalytic performance of Ce_1-xZr_xO₂ nanorods is attributed to the formation of the CeO₂-ZrO₂ solid solution, which contributes to abundant moderate acidic–basic active sites on the catalyst surface. It is the synergistic effect of moderate acidic–basic sites that dominates the conversion of CO₂ with epoxides, which will supply important references for the synthesis of efficient metal oxide catalyst for the cycloaddition of CO₂ with epoxides. Full article

(This article belongs to the Special Issue Catalytic Transformations of CO₂ into High Valuable Products)

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9 pages, 2024 KB

Open AccessArticle

High Catalytic Performance and Sustainability of Zr Modified Aluminophosphate for Vapor-Phase Selective O-Methylation of Catechol with Methanol

by Xinfeng Ren, Dongfei Xu, Yuchen Yin, Xiujing Zou, Yankai Wang, Xingfu Shang and Xueguang Wang

Catalysts 2021, 11(6), 740; https://doi.org/10.3390/catal11060740 - 16 Jun 2021

Cited by 3 | Viewed by 2384

Abstract

Guaiacol produced by O-methylation of catechol with methanol over solid catalysts is a green environmental synthesis route. In order to achieve high catalytic efficiency, it is quite necessary to employ low-cost catalysts with high activity and stability. Herein, series of aluminophosphate catalysts were synthesized by a simple precipitation route modified by Zr. The characterization results indicated that the prepared Al-P-Zr catalysts possessed appropriate weak acid and weak base sites, which were beneficial for the O-methylation of catechol with methanol. Different Zr amount and calcined temperature exerted a significant influence on physicochemical properties of the catalysts and catalytic performance. The Al-P-Zr catalysts containing Zr/Al molar ratio of 0.012 calcined under 400 °C showed the optimal catalytic activity and long-term stability for vapor-phase selective O-methylation of catechol with methanol. Full article

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14 pages, 2071 KB

Open AccessArticle

Purifying of Waste Tire Pyrolysis Oil Using an S-ZrO₂/SBA-15-H₂O₂ Catalytic Oxidation Method

by Muhammad Nobi Hossain, Myung Kyu Choi, Hoon Chae Park and Hang Seok Choi

Catalysts 2020, 10(4), 368; https://doi.org/10.3390/catal10040368 - 30 Mar 2020

Cited by 17 | Viewed by 4358

Abstract

Heavy fuel oils contain a high amount of sulfur. In this work, an extent amount of sulfur content waste tire pyrolysis oil (WTPO) was used as a fuel feedstock. A promising alternative oxidative desulfurization (ODS) method was applied in sulfur removal from WTPO using a S-ZrO₂/SBA-15 solid acid catalyst, hydrogen peroxide (H₂O₂) as an oxidant and acetonitrile as an extracting solvent at varied conditions. The prepared catalyst was characterized by X-ray diffraction (XRD), Bruanuer-Emmet-Teller (BET) method and Fourier transform infrared spectroscopy (FTIR) analysis. The influence of reaction parameters such as reaction time (30-60 min), catalyst loading (0.5–1.5 wt.%), oxidant to oil mole ratio (5–15) at fixed reaction temperature 70 °C on desulfurization of WTPO were investigated. Taguchi method was selected to design the experiment for optimizing the reaction parameters by maximizing the sulfur removal efficiency. The maximum desulfurization efficiency 59.49% was obtained under optimum conditions reaction time (60 min), catalyst loading (1.0 wt.%) and oxidant to sulfur mole ratio (10:1). A catalytic S-ZrO₂/SBA-15 -H₂O₂ oxidation system for oxidative desulfurization of waste tire pyrolysis oil using at mild reaction conditions was developed. Full article

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11 pages, 2404 KB

Open AccessArticle

Valorization of Rare Earth Elements from a Steenstrupine Concentrate Via a Combined Hydrometallurgical and Pyrometallurgical Method

by Yunbo Yun, Srecko Stopic and Bernd Friedrich

Minerals 2020, 10(3), 248; https://doi.org/10.3390/min10030248 - 9 Mar 2020

Cited by 11 | Viewed by 5056

Abstract

Due to their unique characteristics, Lanthanides series (15 elements) together with scandium and yttrium are used as critical metals in numerous applications such as energy sources, catalysts, hybrid cars, medical technology, and military industry. The significance of rare earth elements has been continuously increasing because the global demand for producing high-tech devices is continuously rising. The recovery of rare earth oxide from concentrate based on eudialyte and steenstrupine was performed using a hydrometallurgical and pyrometallurgical method. Eudialyte and steenstrupine are a complex Na-Ca-zirconosilicate mineral containing rare earth elements (REEs), Zr, Hf and Nb, thus serving as a potential source of Zr. Because of the presence of silica in eudialyte, the main challenge in its processing is avoiding silica gel formation, which is an unfilterable solid residue. The influence of leaching temperature, time and solid–liquid ratio on leaching efficiency was studied in laboratory conditions. A new research strategy was developed in order to recover rare earth elements using hydrochloric acid, avoiding silica gel formation. Full article

(This article belongs to the Special Issue Advances in Valorization of Valuable Metals)

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