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Phosphotungstic acid samples supported on nano γ-Al2O3 with the loading of (0.5–40 wt/wt%) were prepared by impregnation and calcined at different temperatures for 3 h. The catalysts were characterized by thermogravimetry, differential thermal analysis, X-ray diffraction and N2 sorption measurements. The acidity of the catalysts was investigated by the dehydration of isopropanol, chemisorption of pyridine and 2,6-dimethyl pyridine. The gas-phase dehydration of ethanol was carried out at 190 °C in a conventional fixed-bed flow type reactor at 1 atm using N2 as a carrier gas. All catalysts calcined at 500 °C exhibited high selectivity toward diethyl ether (DEE) formation. Moreover, the catalyst of 20% phosphotungstic acid supported on γ-Al2O3, AlW20, showed the best selectivity (99%) with 74% yield of DEE. The catalytic performance of supported catalysts were correlated with the strong and intermediate Bronsted acid sites due to presence of Keggin structure and WO3.

A series of single and mixed oxide nanocatalysts of mesoporous CuO-Fe2O3 with different CuO contents (1–50 wt.%) were prepared by a co-precipitation method and further promoted by trace amounts of CeO2, ZrO2 and Ag2O (0.1–0.5 wt.%) dopants. The original and calcined catalysts were characterized by TG, DTA, XRD, TEM, VSM, N2 sorption analysis, surface chemisorbed oxygen and DC electrical conductivity measurements. The catalytic performance of these nanocatalysts toward CO oxidation was studied using a conventional fixed bed flow type reactor. The results revealed that the addition of 1–20 wt.% CuO to Fe2O3 monotonically increases the specific surface area, the amount of surface chemisorbed oxygen, electrical conductivity and catalytic activity of the nanocatalysts. In addition, the catalytic activity indicated that Fe-Cu mixed oxide nanocatalyst promoted with the three dopants (CeO2, ZrO2 and Ag2O) exhibited the highest catalytic activity with a total conversion of CO into CO2 at 100 °C. Moreover, the activation energy of CO oxidation decreased from 38.4 to 23.1 kJmol−1 upon treating the catalyst containing 20 wt.% CuO with the three dopants. Finally the effects of various operational parameters were also studied.

CuO–NiO nanocomposite catalysts were synthesized by an oxalate precipitation route. The basicity of the catalysts was measured using adsorption–desorption of acetic acid. The catalytic conversion of isopropanol to acetone was carried out in a conventional fixed bed flow type reactor at 200 °C using N2 as a carrier gas. The results indicated that, the addition of NiO to CuO greatly enhanced the electrical conductivity via the creation of new charge carriers (Cu+–Ni3+). In addition, the results revealed that the catalyst containing 30 wt.% NiO calcined at 400 °C possesses the highest catalytic activity with 98% conversion and 100% selectivity to acetone. The remarkable catalytic performance of the synthesized catalysts is attributed to the decrease of the energy gap, the increase in the concentration of charge carries (Cu+–Ni3+), and to the creation of more weak and intermediate basic sites.

WO3 catalyst was prepared by thermal decomposition of ammonium metatungstate (AMT) in a static air atmosphere for 3h at 450, 550, 650 and 750℃. The techniques employed for characterization of the catalyst were TG, DTA, XRD, FTIR, N2-sorption measurements. The surface acidity of the catalyst was investigated by adsorption of pyridine and 2, 6-dimethyl pyridine. The catalytic properties of the catalyst were carried out for the dehydration of isopropyl and methyl alcohols. The results revealed that WO3 is more active toward isopropanol dehydration than methanol dehydration. Also reflect that the reaction mechanism and the yield of propene and dimethyl ether produced from dehydration of isopropyl and methyl alcohols are controlled by the strength of acid sites.

Samples of WO3 supported on γ-Al2O3 with loadings w(WO3) = 1–30 % were prepared by impregnation method and subjected to heat treatment at 500 and 550 °C for 3 h in a static air atmosphere. The catalysts were characterized by TG, DTA, XRD, TEM, TPD-pyridine, and N2 sorption measurements. The surface acidity of the catalysts was investigated by the dehydration of isopropanol and the adsorption of pyridine and 2,6-dimethylpyridine. Catalytic activity and selectivity of the catalysts were investigated for the dehydration of methanol to dimethyl ether at 230 °C in a conventional fixed bed flow type reactor at atmospheric pressure using nitrogen or air as a carrier gas. The results revealed that the catalysts with w(WO3) = 1–5 % loadings, calcined at 500 °C, exhibit a considerable increase in the catalytic performance toward methanol dehydration. The increase was, however, much more pronounced with the catalyst containing w(WO3) = 5 %, which attained dimethyl ether in 89 % yield.

Hydroxyapatite (HAP) was synthesized by sol–gel method. Different ratios of molybdenum oxide (1–15 % w/w) supported on HAP were prepared by the impregnation method and calcined at 400 °C in a static air atmosphere. The catalysts were characterized by thermogravimetry, differential thermal analysis, X-ray diffraction, FTIR spectroscopy and nitrogen sorption measurements. The surface acidity of the catalysts was investigated by the dehydration of isopropyl alcohol and the adsorption of pyridine (PY) and 2,6-dimethyl pyridine (DMPY). The gas–phase oxidation of methanol to formaldehyde was carried out in a conventional fixed-bed flow type reactor using N2 as a carrier gas. The obtained results clearly revealed that HAP–MoO3 systems were active and selective towards the formation of formaldehyde. The maximum yield of formaldehyde (97 %) was achieved on the catalyst containing 5 wt% MoO3/HAP. The generation of Mo6+as Lewis together with Bronsted acid sites play the main role in the formation of formaldehyde. Catalytic oxidation of methanol over MoO3/HAP calcined at 400 °C for 4 h.

A series of ZrO2/γ-Al2O3 catalysts were prepared by incipient wetness impregnation of zirconyl nitrate hydrate aqueous solutions on nano-γ-Al2O3 with ZrO2 loadings (1–30 % w/w) and calcined at 450 and 550 °C for 3 h in a static air atmosphere. Physicochemical properties of the catalysts were determined using TG, DTA, XRD, FT-IR, Raman spectroscopy, TEM, and N2 sorption measurements. The surface acidity of the catalysts was investigated by dehydration of isopropanol and adsorption of pyridine, 2,6-dimethyl pyridine and TPD–pyridine. This series of catalysts was used for vapor-phase dehydration of methanol to dimethyl ether in a fixed bed reactor. It was found that all catalysts in this study were active and selective for DME synthesis. According to the experimental results, 1 % ZA catalyst exhibited the highest activity with selectivity of 100 % toward DME.

Sulfated zirconia catalysts were prepared by wetness impregnation of zirconium hydroxide with an aqueous solution of (NH 4 ) 2 SO 4 with SO 4 2− loadings (1–30%, w/w) and calcined at 450 °C for 3 h in a static air atmosphere. The catalysts were characterized by FT-IR, XRD, TEM and BET measurements. The surface acidity of the catalysts was investigated by the dehydration of isopropanol and the adsorption of pyridine (PY) and 2,6-dimethyl pyridine (DMPY). The catalysts were tested for dehydration of methanol in a fixed-bed reactor at 230 °C using air as a carrier gas. The results revealed that among different catalysts, 10% SO 4 2− supported onto zirconia showed the highest catalytic activity with 83% conversion and 100% selectivity toward dimethyl ether. A good correlation was found between the acidity of the catalysts and their ability to dehydrate methanol.

The Scan Electron Microscope Images (SEM), X-ray Diffraction and Fourier Transform Infrared Spectroscopy (FTIR) dataset has been outlined investigating morphological features change of native sugarcane bagasse, as an agro-industrial lignocellulosic feedstock waste and a potential for cellulose biopolymer extraction, pretreated by alkali (sodium hydroxide) followed by an acid step (sodium bisulfate) in an exothermic in-situ one step, pretreated by acid (sulfuric acid) followed by residual solid fraction alkali pretreatment (sodium hydroxide) in a two separate individual steps and finally after the enzymatic cellulolysis. Data explained herein helps to extend and add to knowledge regarding the impact unlikeness of two different pretreatment methodologies utilize the same chemicals and relatively same concentrations on the cellulosic fiber morphological features and consequently its enzymatic accessibility. This data are related to Egypt Patent Office application, 1349/2017, entitled “In-situ sodium hydroxide-sodium bisulfate sugarcane bagasse pretreatment for biofuel production”,Zohri et al., 2017 [1]. Keywords: Biomass, Pretreatment, In-situ, Cellulose, Enzymatic hydrolysis, Biofuel

A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the NiC2O4.2H2O and/or CuC2O4 precursors which obtained via the reaction between alcoholic metal nitrates and oxalic acid solutions. Thermal behavior of the single and mixed salts has been studied using thermal analysis (TG and DTA). Thermal products were characterized using Fouier transform infrared (FTIR), X-ray diffraction (XRD), Electron microscopy (SEM&TEM), Nitrogen adsorption at -196 o C and surface excess oxygen measurements. The results revealed that, pure NiC2O4.2H2O and CuC2O4 decomposed at 355 and 325 o C, respectively. Also, it was found that the addition of NiO to CuO brought a significant increase in the degree of crystallinity of the mixed oxides which is accompanying with an increase in their particle size and a decrease in the surface area. Moreover, addition of NiO to CuO, also reduces the amount of surface excess oxygen of CuO due to a synergistic effect.

This research work involved the use of the low cost, available and renewable biosorbent propionic acid pretreated bagasse for the removal of the textile direct yellow 12 and direct red 81 dyes from aqueous solutions. Batch experiments were carried out for sorption kinetics and isotherms of the two dyes. The studied operating variables include initial pH, contact time, initial dye concentration, adsorbent dose and particle size. Maximum color removal was in acidic medium (pH 2.5-3.5) where a greater percentage removal was observed in this pH range. Equilibrium isotherms were applied using Langmuir and Freundlich models of adsorption and it was found that the Langmuir isotherm was the best model for adsorption of direct yellow 12 whereas the Freundlich model was suitable for adsorption of the direct red 81. The kinetics of adsorption of both dyes was consistent with a pseudo-first order kinetic for the direct yellow 12 and a pseudo-second order for the direct red 81. Desorption of both dyes is greatly dependent on the pH value of the solution with which the bagasse loaded dye in contact. The percent dye removal increases with the pH increase.

Propionic acid modified bagasse was used for the removal of reactive yellow 2 and reactive blue 4. The effects of pH, contact time, initial dye concentrations, adsorbent particle size and adsorbent dose on the adsorption of the two dyes were investigated. Additionally, the desorption process and intra-particle diffusion were studied. Acidic pH values were favorable for adsorption of both dyes. The equilibrium adsorption data were best fitted with the Freundlich isotherm for reactive yellow 2 and the Langmiur isotherm for reactive blue 4. The values of their corresponding constants were determined. The kinetic for dye adsorption is well described by a pseudo-first order kinetic model for the reactive yellow 2 and by pseudo-second order for the reactive blue 4. The investigation revealed that the hydroxyl groups of bagasse and the carboxylic group of propionic acid play a great role in the removal of both reactive dyes.

Raw sugarcane bagasse modified with propionic acid (RBMPA) was used as an efficient, low cost and eco-friendly adsorbent for the removal of methylene blue (basic) and orange II (acid) dyes from aqueous solutions. The effect of different system variables, namely contact time, dye concentration, adsorption dose, pH and particle size were investigated and optimal experimental conditions were ascertained. A greater percentage of dye removal was observed in acidic medium (pH=2) in case of orange II whereas in (pH=7) in case of methylene blue dyes and increases with the increase of the dosage of adsorbent. Maximum dye removal was attained after 60 min. Equilibrium isotherms were analysed by the Langmuir and Freundlich models of adsorption and it was found that the Langmuir isotherm provides a good model for the adsorption of methylene blue whereas the Freundlich isotherm is fit for the adsorption of orange II. The kinetics of the adsorption of both dyes was consistent with pseudo second-order kinetics with a good correlation (R2 > 0.99). Furthermore, the amounts of dye adsorbed at equilibrium, qe (mg g-1) for methylene blue and orange II were 59.5 and 25.5, respectively.

Different ratios of phosphotungestic acid supported on silica gel were prepared by an impregnation method with PWA loadings ranging from 1 to 30% w/w and calcined at 350 and 500 °C for 4 h in a static air atmosphere. The catalysts were characterized by thermogravimety (TG), differential thermal analysis (DTA), X-ray diffraction, FT-IR spectroscopy and N2 adsorption measurements. The surface acidity and basicity of the catalyst were investigated by the dehydration–dehydrogenation of isopropanol and the adsorption of pyridine (PY) and 2,6-dimethyl pyridine (DMPY). The gas-phase estrification of acetic acid with ethanol was carried out at 185 °C in a conventional fixed-bed reactor at 1 atm using air as carrier gas. The results clearly revealed that the catalyst containing 10% w/w PWA/SiO2 is the most active and delivers reaction selectively to ester with 85% yield. The Bronsted acid site resulting from hydroxylation of tungsten oxide plays the main role in the formation of ester. Copyright © 2007 Society of Chemical Industry

A series of MoO3/SiO2 catalysts was prepared by an impregnation method with Mo loadings ranging from 1 to 50 wt%. The original and calcined samples at 400 °C were characterized by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and nitrogen adsorption measurements. The surface acidity and basicity of the catalysts were investigated by the dehydration–dehydrogenation of isopropanol and the chemisorption of pyridine. The catalytic esterification of acetic acid with ethanol was carried out at 220 °C in a conventional fixed-bed reactor at 1 atm using air as a carrier gas. The results clearly revealed that silica–molybdena catalysts were active and selective towards the formation of ethyl acetate. Moreover, the catalyst containing 20 wt% MoO3 was the most active and selective one. The results emphasize the importance of the surface acid sites together with the specific surface area of the prepared catalyst, towards ester formation. Copyright © 2005 Society of Chemical Industry

A series of AlPO4-V2O5 (APV) systems with various vanadia amounts 1–30 mol% were prepared by the impregnation method and calcinated at 400 and 600°C for 4 h. The catalysts were characterized by TG/DTG, DSC, IR spectroscopy, XRD, N2 adsorption, and electrical conductivity measurements. The surface acidity and basicity of the catalysts were studied by the dehydration-dehydrogenation of isopropyl alcohol and the adsorption of pyridine. The catalytic gas phase esterification of acetic acid with ethyl alcohol was carried out at 210°C in a flow system at 1 atm using air as a carrier gas. The results showed that the catalysts calcinated at 400°C were active and selective towards the formation of ethyl acetate whereas the calcination of samples at 600°C led to a drastic reduction in both activity and selectivity. Good correlations were obtained between catalytic activities towards ester formation and acidity of the prepared catalysts.

The catalytic dehydrogenation of ethyl alcohol on vanadium pentoxide supported on magnesia was studied in a flow system. The catalysts were characterised by DTA, X-ray, surface area and electrical conductivity measurements. The results revealed that the yield of acetaldehyde is strongly affected by the nature of compounds formed as a result of the interaction between MgO and V 2 O 5 . The Mg 3 V 2 O 5 formed at a calcination temperature of 550°C is the most active and selective catalyst. The activity of this spinel was correlated with the creation holes and the position of the Fermi potential. On the other hand, the catalyst calcined at 650°C was accompanied by the formation of an MgV 2 O 6 spinel, which exhibited low activity and low selectivity

The cobalt ferrite spinel oxide series, CoxFe3–xO4 (0 ≤ x ≤ 3), has been prepared by coprecipitation. The adsorption–desorption isotherms of all the compositions calcined between 200 and 600°C have been measured using nitrogen gas at −196°C. The structural and the phase changes were characterized by TGA and XRD techniques. The results obtained revealed that the transformation of γ- to α-Fe2O3 was accompanied by a sharp decrease in the SBET values. The addition of Co2+ ions into Fe2O3 up to × = 0.6 led to an observable increase in the SBET value. This behaviour was attributed to the incorporation of Co2+ ions into the Fe2O3 lattice and the retardation of the phase transition of γ- to α-Fe2O3. The minimum SBET values obtained at a lattice composition of × = 1·0 corresponded to the formation of a cobalt ferrite normal spinel which is associated with the existence of narrow pores. The increase in SBET values in the cobalt-rich region, with a maximum at x = 2·6 is explained on the basis of the cationic replacement of Fe3+ ions in the Co3O4 lattice. Finally, calculation of pore volume distribution was carried out, in addition to Va–t plots, in order to study the nature of the surface porosity, which was found to be mesoporous.

Vanadium pentoxide catalysts supported on γ-alumina (1 - 50 mole %) were prepared by impregnation method and calcined at 400 and 680 °C for 4 h. The structure of the original and calcined samples was characterized by DTA and X-ray diffraction. The electrical conductivity measurements of the calcined samples reveal that the conductance increases while the Fermi potential decreases on increasing V2O5 content up to 50 mole %. The catalytic dehydration of isopropanol was carried out at 250 °C using a flow system. The results showed an observable increase in the extent of catalytic dehydration of the alcohol on increasing V2O5 content from 5 mole % to 50 mole % with the samples calcined at 400 °C. The catalysts calcined at 680 °C were found to exhibit maximum activity at the composition of 20 mole % V2O5. Above the maximum a sharp decrease in the conversion and the yield towards propylene was found due to formation of aluminium vanadate, i.e. AlVO4 spinel. The low activity associated with the existence of this spinel was correlated with the sharp decrease in the Fermi potential.

The cobalt ferrite spinel oxides CoxFe3-xO4 (O < x < 3) have been prepared by coprecipitation. Their structures were characterized by DTA, X-ray diffraction and IR spectra, and their surface properties were determined from nitrogen adsorption isotherms at -196 °C. Conductance of all the compositions was studied with and without isopropanol. The variation of Eσ values was discussed in terms of oxide semiconducting properties and of ion distribution in the octahedral-tetrahedral sites of the spinel structures. The catalytic decomposition of isopropanol at 325 °C in a flow system allowed to conclude that the inverse spinels formed in the iron-rich region are active and selective sites for acetone formation, in contrast to the inverse spinels formed in the cobalt-rich region. On the other hand, the region of normal spinels showed low activity and selectivity to acetone formation. Correlations between the composition and electronic and catalytic properties of the catalysts are reported.

A study of the non-isothermal decomposition of new aromatic polyphosphates (I–V) based on diarylidenecycloalkanone moieties has been carried out using TGA measurements at atmopsheric pressure. Analysis of non-isothermal TG and DTG curves of these polyphosphate esters indicated that their decompositions proceed in three stages. Kinetic parameters such as activation energy (Ea), pre-exponential factor (A) and entropy of activation (ΔS∗) for the whole samples at different decomposition stages are determined. The data showed that the thermal stability of polymers I–III decreases with increasing ring size of the diarylidenecycloalkanone moieties. The effect of the presence of -OCH3 groups upon the thermal properties of polymers is also discussed.

A new interesting category of organometallic polyesters based on diarylidenecycloalkanones containing ferrocene derivatives in the polymer main chain has been prepared by interfacial polycondensation of 1,1′-dichlorocarbonyl ferrocene or 1,1′-dichlorocarbonyl-4,4′-diiodoferrocene with 2,5-bis(p-hydroxybenzylidene)cyclopentanone, 2,5-divanillylidenecyclopentanone, 2,6-bis(p-hydroxybenzylidene)cyclohexanone, 2,6-divanillylidenecyclohexanone, and 2,7-bis(p-hydroxybenzylidene) cycloheptanone. The resulting polyesters were characterized by elemental analyses, infrared spectroscopy, solubility, and viscometry measurements. The thermal behavior of the synthesized polymers was evaluated by thermal gravimetric analysis and correlated with their structures. The crystallinity of all polymers were examined by x-ray diffraction analysis. Moreover, the electrical conductivity of a selected example of polymer was investigated above the temperature range (300–500 K) and showed that it followed an Arrhenius-type equation with activation energy 2.09 eV. © 1993 John Wiley & Sons, Inc.

Studies of non-isothermal decomposition of certain iodo-organometallic arylidene polyesters and organometallic arylidene polyesters have been performed with TGA measurements at atmospheric pressure. The analysis of the non-isothermal TG and DTG curves of the samples under investigation revealed that their decomposition course proceeds via three stages. The kinetic parameters such as activation energy (E,), preexponential factor (A) and entropy of activation (AS*) for all polymers at different decomposition stages are determinedfrom an appropriate kinetic equation. More particularly, the data showed that the thermal stability of some of the polymers decreases with increasing ring size of arylidene moieties. Furthermore, the effect of absence of iodoand presence of-OCH3 groups upon the thermal properties of polymers was also evaluated.