Promotion effects of alkali metals on iron molybdate catalysts for CO_(2)catalytic hydrogenation

CO_(2)hydrogenation is an attractive way to store and utilize carbon dioxide generated by industrial processes,as well as to produce valuable chemicals from renewable and abundant resources.Iron catalysts are commonly used for the hydrogenation of carbon oxides to hydrocarbons.Iron-molybdenum catalysts have found numerous applications in catalysis,but have been never evaluated in the CO_(2)hydrogenation.In this work,the structural properties of iron-molybdenum catalysts without and with a promoting alkali metal(Li,Na,K,Rb,or Cs)were characterized using X-ray diffraction,hydrogen temperatureprogrammed reduction,CO_(2)temperature-programmed desorption,in-situ^(57)Fe Mossbauer spectroscopy and operando X-ray adsorption spectroscopy.Their catalytic performance was evaluated in the CO_(2)hydrogenation.During the reaction conditions,the catalysts undergo the formation of an iron(Ⅱ)molybdate structure,accompanied by a partial reduction of molybdenum and carbidization of iron.The rate of CO_(2)conversion and product selectivity strongly depend on the promoting alkali metals,and electronegativity was identified as an important factor affecting the catalytic performance.Higher CO_(2)conversion rates were observed with the promoters having higher electronegativity,while low electronegativity of alkali metals favors higher light olefin selectivity.

Analysis of Heat Transfer Phenomena inside Concrete Hollow Blocks

During both hot and cold seasons,masonry walls play an important role in the thermal performance between the interior and the exterior of occupied spaces.It is thus essential to analyze the thermal behavior at the hollow block’s level in order to better understand the temperature and heat flux distribution in its structure and potentially limit as much as possible the heat transfer through the block.In this scope,this paper offers an experimental and numerical in-depth analysis of heat transfer phenomena inside a hollow block using a dedicated experimental setup including a well-insulated reference box and several thermocouples and fluxmeters distributed at the boundaries and inside the hollow block.The block was then numerically 3D modelled and simulated using COMSOL Multiphysics under the same conditions,properties,and dimensions as the experimentally tested block.The comparison between the numerical and experimental results provides very satisfactory results with relative difference of less than 4%for the computed thermal resistance.

The Vibrational Behavior of the Mixture Quercetin/Gelucire 50/13 at Room and Body Temperature

The present paper discusses the vibrational properties of the mixture gelucire-quercetin(from 1%to 5%)at room and body temperature.Quercetin is a flavonoid having beneficial properties:biological and antioxidant;it is used in many fields as food,cosmetic and especially pharmaceutics but its use as a drug is affected by its low solubility.The Gelucire 50/13 is used as sustained release matrix forming agent in pharmaceutical applications and it has demonstrated the ability to improve the dissolution as well as the absorption of poorly water-soluble drugs.The mixture Gelucire-quercetin was essentially studied by FTIR(Fourier transform infrared spectroscopy)and Raman spectroscopy.The behavior of these two molecules has been investigated in the spectral range 4000-0 cm-1 in Raman spectroscopy,and 4,000-600 cm-1 in FTIR.

Copper-uptake mediated by an ecofriendly zwitterionic ionic liquid: A new challenge for a cleaner bioeconomy

This study aims to investigate the ability of an imidazolium biobased Zwitterionic Ionic Liquids(ZILs)in enhancing the phytoavailability of copper from garden(G)and vineyard(V)soils using the model plant ryegrass.Uncontaminated and artificially contaminated CuSO_(4) soils,unamended and ZIL-amended soil modalities were designed.The copper/ZIL molar ratio(1/4)introduced was rationally established based on molecular modeling and on the maximal copper concentration in artificially contaminated soil.Higher accumulation of copper in the shoots was detected for the uncontaminated and copper contaminated ZIL amended V soils(18.9 and 23.3 mg/kg,respectively)contrary to G soils together with a ZIL concentration of around 3%(W/W)detected by LC-MS analyses.These data evidenced a Cu-accumulation improvement of 38%and 66%compared to non-amended V soils(13.6 and 13.9 mg/kg respectively).ZIL would be mainly present under Cu(II)-ZIL_(4) complexes in the shoots.The impact on the chemical composition of shoot was also studied.The results show that depending on the soils modalitity,the presence of free copper and/or ZIL led to different chemical compositions in lignin and monomeric sugar contents.In the biorefinery context,performances of enzymatic hydrolysis of shoots were also related to the presence of both ZIL and copper under free or complex forms.Ecotoxicity assessment of the vineyard soil samples indicated that the quantity of copper and ZIL remaining in the soils had no significant toxicity.ZIL amendment in a copper-contaminated soil was demonstrated as being a promising way to promote the valorization of phytoremediation plants.

New stabilization conditions for continuous fuzzy models using their discretized forms

Purpose–The purpose of this paper is to deal with the stabilization of the continuous-time TakagiSugeno(TS)fuzzy models by using their discretized models.Design/methodology/approach–In this case,a discrete model is obtained from the discretization of the continuous TS fuzzy model.The gains obtained from a non-parallel distributed compensation controller ensuring the stabilization of the discrete model are used to check if the discrete control law used in the continuous time without any zero-order hold can stabilize the continuous TS model.Findings–This method is compared to another published method.Originality/value–Therefore,the originality of this paper consists in the fusion of the two continuous and discrete cases to obtain new stabilization conditions in the continuous case.Simulation examples show the interest of the proposed approach.

Decay rate performance approach for stabilization continuous fuzzy models using their discretized forms

Purpose–The purpose of this paper is to deal with the stabilization of the continuous Takagi Sugeno(TS)fuzzy models using their discretized forms based on the decay rate performance approach.Design/methodology/approach–This approach is structured as follows:first,a discrete model is obtained from the discretization of the continuous TS fuzzy model.The discretized model is obtained from the Euler approximation method which is used for several orders.Second,based on the decay rate stabilization conditions,the gains of a non-PDC control law ensuring the stabilization of the discrete model are determined.Third by keeping the values of the gains,the authors determine the values of the performance criterion and the authors check by simulation the stability of the continuous TS fuzzy models through the zero order hold.Findings–The proposed idea lead to compare the performance continuous stability results with the literature.The comparison is,also,taken between the quadratic and non-quadratic cases.Originality/value–Therefore,the originality of this paper consists in the improvement of the continuous fuzzy models by using their discretized models.In this case,the effect of the discretization step on the performances of the continuous TS fuzzy models is studied.The usefulness of this approach is shown through two examples.