Kinetic modeling of heterogeneous esterification reaction using initial reaction rate analysis : data extraction and evaluation of mass transfer criteria

This data article provides detailed guidance to obtain heterogeneous reaction rate expressions and the corresponding initial reaction rates and their application. Explanation is provided to deal with specific criteria to rule out internal and external concentration gradients, so that the usage of intrinsic catalytic data is guaranteed. Overall, the main goal is to provide an easy tool to evaluate both aforementioned results by simple plug-and-play of available reaction data

Flexibility in metal–organic frameworks : a basic understanding

Much has been written about the fundamental aspects of the metal-organic frameworks (MOFs). Still, details concerning the MOFs with structural flexibility are not comprehensively understood. However, a dramatic increase in research activities concerning rigid MOFs over the years has brought deeper levels of understanding for their properties and applications. Nonetheless, robustness and flexibility of such smart frameworks are intriguing for different research areas such as catalysis, adsorption, etc. This manuscript overviews the different aspects of framework flexibility. The review has touched lightly on several ideas and proposals, which have been demonstrated within the selected examples to provide a logical basis to obtain a fundamental understanding of their synthesis and behavior to external stimuli

Selective cyclodimerization of epichlorohydrin to dioxane derivatives over MOFs

Glycerol can be converted to valuable products such as epichlorohydrin which is an important intermediate applied in various industries. For example, dioxane derivatives, which are important pharmaceuticals, can be obtained from epichlorohydrin. In the present study, ZIF-8, ZIF-67, MIL-100, and UiO-66 were applied for the direct cyclodimerization of epichlorohydrin. These MOFs were selected because they were already applied as active catalysts in ring opening of epoxides. Among them, ZIF-8 showed the highest activity and selectivity in the absence of any solvent or co-catalyst. Using ZIF-8 as a catalyst, the cyclodimer product (1,4-dioxane 2,5-bis-chloromethyl) was obtained in a yield of about 70% which was significantly superior to previous homo or heterogeneous catalysts for this reaction. Due to ZIF-8 structure and the proposed mechanism, the cyclodimerization reaction catalyzed either by the defects in the structure and/or on the surface. Furthermore, acidic-basic characteristics were also in play. The NH3 and CO2 temperature-programed desorption technique were utilized to identify the active sites and thereby reaction mechanism. Moreover, because of similar properties of ZIF-8 to zeolites, the activity of commercial ZSM-5 for the same reaction was also investigated in this work

Metal-organic frameworks applied for water purification

Metal-organic frameworks (MOFs) which are materials constructed from metal ions/clusters bridged with organic linkers have emerged as an important family of porous materials for widely varying applications. The purification of water polluted with both of organic and inorganic contaminants is a potentially promising application of MOFs since the chemical and thermal properties of the porous materials are easily tunable, e.g. ligand modification, different metal, etc. The demonstration of alignment and theobtained insights facilitate the direction of designing ideal MOF materials with improved water stability for application in water purification. This review gives a brief overview and will be beneficial to the design, functionalization, and promotion of the development of MOFs as adsorbent materials for applications in water purification

Metal-organic frameworks applied for water purification

Metal-organic frameworks (MOFs) which are materials constructed from metal ions/clusters bridged with organic linkers have emerged as an important family of porous materials for widely varying applications. The purification of water polluted with both of organic and inorganic contaminants is a potentially promising application of MOFs since the chemical and thermal properties of the porous materials are easily tunable, e.g. ligand modification, different metal, etc. The demonstration of alignment and theobtained insights facilitate the direction of designing ideal MOF materials with improved water stability for application in water purification. This review gives a brief overview and will be beneficial to the design, functionalization, and promotion of the development of MOFs as adsorbent materials for applications in water purification

MoO3NPs/ZIF-8 composite material prepared via RCVD for photodegradation of dyes

Toxic wastewaters from the textile industry have made its way into rivers and other waterways, posing a serious health treat on both human and wildlife. Herein, this data set presents the potential use of MoO3 nanoparticles supported on ZIF-8 in the photodegradation of a cationic dye molecule. The data presented in this article report a concise description of experimental conditions for the spray dried ZIF-8 synthesis and subsequent deposition of MoO3 nano particles via rotary chemical vapor deposition (RCVD). The photodegradation and analysis data reviled that the MoO3-NPs@ZIF-8 3 wt% displayed the ability of degrading methylene blue up to 82% and 95% after 180 and 300 min, respectively

Effects of temperature on methanol adsorption on functionalized graphite: saturation of functional groups

Grand Canonical Monte Carlo simulation of methanol adsorption on a graphite model with two hydroxyl groups grafted on the surface has been carried out to investigate the effects of temperature in the range of 278–360 K. The spacing between the OH groups was chosen so that two hydrogen bonds could be formed with the first methanol molecule. In the Henry law region, the isosteric heat at zero loading is greater than the condensation heat. When the loading is increased, the isosteric heat at low temperatures decreases slightly and exhibits a shoulder, which is associated with the formation of a cluster of methanol molecules around one OH group. On further increase in loading, the adsorbate–adsorbate interactions decrease because methanol begins to adsorb on the other OH group, resulting in a sharp decrease in the isosteric heat to a minimum, at which point both OH groups are covered with methanol molecules. At higher temperatures the isosteric heat at zero loading decreases but remains higher than the condensation heat. The shoulder heat is progressively diminished with temperature because methanol molecules are distributed over the two OH groups, due to the entropic effects. Interestingly, the minimum heat still occurs when the functional groups are covered and is even more pronounced at high temperatures

From biogas to biofuel : materials used for biogas cleaning to biomethane

Biomethane is one of the biofuel sources produced from biogas which is an important source of renewable energy. Since it is an alternative and clean energy source, its implementation as fuel source applying established energy infrastructure is an attractive opportunity. However, biogas as a source of biomethane contains undesirable compounds, e.g., H2S, NH3, siloxanes, water, etc. and needs to be decontaminated before usage. Biogas cleaning technologies are presented from a material point of view along with their property modifications. A brief discussion of materials applied in technologies with a particular emphasis on biogas cleaning is followed by the alternative properties and possibilities of liquid and solid adsorbents as well as chemical reactions used for biogas cleaning to produce biomethane suitable as fuel source to replace or reduce fossil fuel consumption

Kinetic modeling of oleic acid esterification with UiO-66 : from intrinsic experimental data to kinetics via elementary reaction steps

This work reports the experimental conversion of oleic acid (OA) into methyl oleate via UiO-66 MOF catalyst. Strong focus is on the kinetic modeling: 67 models, based on elementary reaction steps for Eley-Rideal, Langmuir-Hinshelwood and Hattori kinetic mechanisms, are proposed. Via the application of initial reaction rate theory and nonisothermal kinetic modeling, one model adequately describes the experimental data. It is a variant on the Eley-Rideal type of model, such that the surface reaction includes the oleic acid adsorbate, methanol reacts from the liquid phase and one additional active site is considered to make the ester and water as surface reaction products, so that overall two active sites are used in the surface reaction. An activation energy of 54.9 +/- 1.8 kJ mol(-1) is reported and the desorption of the ester was found to be irreversible. In addition, NH3 TPD revealed at least two types of acid sites (#) on the UiO-66 MOF, from which turnover rates were calculated in the range of 2.54 +/- 0.33 to 8.82 +/- 0.87 mmol(OA) mol(#)(-1) s(-1). Since the catalyst is recyclable and no additional acids have to be used, this system can be considered as a green alternative for the well-known homogeneously catalyzed esterification reaction

Ring-opening polymerization of L-lactide to cyclic poly(lactide) by zeolitic imidazole framework ZIF-8 catalyst

The catalytic activity of ZIF-8 in the ring-opening polymerization of l-lactide without solvents or cocatalysts is presented for the first time. Two different synthetic strategies have been applied for synthesizing ZIF-8, either under solvothermal condition or by spray-drying procedure. Their catalytic activities are found to be correlating with the presence of open active sites in ZIF-8 structure. The structural defects that afford active acid and basic sites are supposed to cooperatively catalyze the reaction. ZIF-8 assembled by spray-drying technique, displays a superior catalytic activity at temperature of 160 degrees C, leading to the formation of high molecular weight cyclic polylactide. The ZIF-8 catalysts could be recycled and reused without any significant loss of catalytic activity