Spray Impregnation Research Articles

Study of metal sequenced spray impregnation method towards Co-Mo/γ-Al2O3 catalytic performance in hydrotreating of used coconut oil to liquid biohydrocarbon

A series of bifunctional catalyst CoMo on γ-Al2O3 have been successfully prepared using the spray impregnation (dry impregnation), with the variation in the metal sequence (Co-Mo and Mo-Co) and metal impregnation time gap (1-h, 24-h, and simultaneous). XRF indicated that the developed method causes a minimal amount of metal loss during the impregnation process. XRD shows that 24-h treatment reduces crystallinity compared to the 1-h and simultaneous catalysts. Co and Mo existed as CoAl2O4, CoO, and MoO3 as reported by XANES and XPS. The preparation technique signified the catalyst's acidity and surface area. The Co-Mo/γ-Al2O3 24H has a high surface area (118.32 m2 g−1), with a pore volume of 0.22 cm3 g−1, and a pore diameter of 7.48 nm. It has a high proportion of weak acid sites (41.32 %) which is crucial to perform HDO reactions. Co-Mo/γ-Al2O3 24H showed high catalytic activity (40.32 wt% liquid product) and selectivity (85.61 % of biogasoline and 9.75 % of diesel fractions) from the hydrotreatment. Kimi@UGM2010.

Numerical analysis of residence time for particle impregnation in a rotating drum

The impregnation is a key step for handling particles in various chemical engineering processes, which requires uniform distribution of active ingredients over particles. This paper describes the effects of particle residence time in the impregnation area on the inter-particle impregnation variability in a rotating drum. The discrete element method is used to simulate the particle dynamics and the image analysis method is used to model the spray impregnation process. It is observed that the coefficient of inter-particle impregnation variability decreases over time and converges to an asymptotic value, which depends on the particle size and the width of the impregnation area. The dead zone of impregnation near the inclined side walls of the drum is identified, which can be reduced by widening the impregnation area. In addition, the relative standard deviation of residence time for particles in the impregnation area also decrease with the increase of particle size and impregnation area width. With various particle sizes and impregnation areas, it is found that the inter-particle impregnation variability is linearly related to the relative standard deviation of the residence time of the particles in the impregnation area, since the exposure of particles in the spray area controls the impregnation over particles. This study provides fundamental insights for optimizing the particle impregnation process in a rotating drum.

Novel Nanostructured Pd/Co-Alumina Materials for the Catalytic Oxidation of Atmospheric Pollutants.

Cobalt-doped alumina catalysts were prepared using different methods, either conventional wet impregnation (WI) and/or advanced spray impregnation (SI), and they were evaluated as novel oxidation catalysts for CO and MeOH oxidation. The spray impregnation technique was used with the aim of achieving the synthesis of core-shell catalytic nanostructures to secure the chemical/thermal stability of active sites on the catalyst carrier. The catalysts were further promoted with a low Pd content (0.5 wt.%) incorporated via either incipient wetness impregnation (DI) or spray impregnation. The results revealed the superior performance of the spray-impregnated catalysts (Co/γ-Al2O3-SI) for both reactions. The deposition of Co oxide on the outer surface of the alumina particle (SEM images) and the availability of the active Co phase resulted in the enhancement of the Co/γ-Al2O3 catalysts' oxidation activity. Pd incorporation increased the catalysts' reducibility (TPR-H2) and improved the catalysts' performance for both reactions. However, the Pd incorporation method affected the catalytic performance; with the SI method, the active phase of Co3O4 was probably covered with PdO and was not available for the oxidation reactions. On the contrary, the incorporation of Pd with the DI method resulted in a better dispersion of PdO all over the Co/Al catalyst surface, maintaining available Co active sites and a better Pd-Co interaction. MeOH desorption studies revealed the methanol oxidation mechanism: the Co/Al catalysts promoted the partial oxidation of MeOH to formaldehyde (HCHO) and dehydration to dimethyl ether (DME), while the Pd-based Co/Al catalysts enhanced the complete oxidation of methanol to CO2 and H2O.

In-situ spray impregnation of poly(pentamethylene oxamide) onto carbon fibers and their composites

Polyoxamides are a class of polyamides that exhibit superior mechanical, chemical, UV light resistance, and low water absorption properties than their conventional counterparts. In this study, a novel in-situ spray polycondensation techniques is developed and used to impregnate poly (pentamethylene oxamide) (PA52) prepolymer into carbon fibers (CF). The prepolymer impregnated CFs are subjected to solid state polycondensation to increase the molecular of PA52 resin thus obtain prepregs for fabrication of carbon fiber reinforced polyoxamide composites. The effects of preparation parameters on the mechanical properties of PA52/CF composites are studied and reported. The results showed that, PA52/CF composites prepared at molding temperature of 325°C, pressure of 3.0 MPa, and time of 10 min exhibits good tensile strength at break, flexural strength, and interlaminar shear strength (ILSS) of 435 MPa, 364 MPa, and 51 MPa, respectively. SEM results suggest good adhesion between the PA52 and CF which is supported by the high storage modulus results obtained from dynamic mechanical analysis (DMA) results, depicting the potential of in-situ spray impregnation in preparation of carbon fiber reinforced polyoxamide composites.

Rosin acid and SiO2 modified cotton fabric to prepare fluorine-free durable superhydrophobic coating for oil-water separation

Currently, fluorides and long-chain aliphatic compounds are the most frequent low surface energy chemicals utilized in the preparation of superhydrophobic coatings, but associated environmental risks and instability restrict their potential application in oil-water separation. This research described a superhydrophobic coating based on rosin acid and SiO2 modified cotton fabric to overcome this challenge. By means of spray impregnation and UV-assisted click reaction, sulfhydryl modified rosin acid (RA), Octavinyl-POSS, and SiO2 were grafted onto the surface of cotton fabric to obtain RA-SiO2 superhydrophobic coating with rough surfaces such as lotus leaf and low surface energy. The RA-SiO2 superhydrophobic coating had favorable self-cleaning ability, and also adsorbed various light and heavy oils to achieve efficient separation of oil-water mixtures. The separation efficiency was 96.3% and the permeate flux was 6110.84 (L⋅m−2⋅h−1) after 10 repetitions. The RA-SiO2 superhydrophobic coating was found to be effective in separating oil-in-water and oil-in-water emulsions, and the separation mechanism was elaborated. In addition, it could effectively separate emulsions even after mechanical abrasion and chemical immersion, and had excellent stability. The fluorine-free and environmentally friendly low-cost superhydrophobic coating based on rosin acid is expected to play a significant potential in oil-water separation applications due to its excellent separation performance.

On the role of potassium as a tar and soot inhibitor in biomass gasification

The work investigates in a drop tube furnace the effect of potassium on carbon conversion for three different types of fuels: an ash lean stemwood, a calcium-rich bark and a silicon-rich straw. The study focuses on an optimal method for impregnating the biomass with potassium. The experiments are conducted for 3 different impregnation methods; wet impregnation, spray impregnation, and dry mixing to investigate different levels of contact between the fuel and the potassium. Potassium is found to catalyse both homogenous and heterogeneous reactions. All the impregnation methods showed a significant effect of potassium on heterogeneous reactions (char conversion). The fact that dry mixing of potassium in the biomass shows an effect reveals the existence of a gas-induced mechanism that supply and distributes potassium on the char particles. Concerning the effect of potassium on homogenous reactions, it is found that potassium in the gas phase leads to much lower yields of C2 hydrocarbons, heavy tars and soot. The results indicate that potassium reduces the likelihood of light aromatic to progress toward heavier polyaromatic hydrocarbons clusters, thereby inhibiting the formation of soot-like material. A moderate interaction between the added potassium and the inherent ash forming elements is also observed: Potassium has a smaller effect when the fuel is naturally rich in silicon. The combined results are of interest for the design of a gasification process that incorporates recirculation of naturally occurring potassium to improve entrained flow gasification of biomass.

Enhancing catalysis activity of La0.6Sr0.4Co0.8Fe0.2O3-δ cathode for solid oxide fuel cell by a facile and efficient impregnation process

Abstract The development of high performance electrocatalysts to promote oxygen reduction reaction (ORR) and to prolong the durability of cathodes of solid oxide fuel cell is essential at intermediate or low temperatures. Here, we report a facile and efficient spray impregnation strategy in enhancing catalytic activity of La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) due to the introduction of a multitude of homogeneous nanoparticles. With a highly active surface abundance in B-site cations, the modified LSCF cathode manifests an area-specific resistance (ASR) of ∼0.140 Ω cm2, only a fifth of that for a pristine LSCF cathode (∼0.764 Ω cm2) at 600 °C, and anode-supported fuel cells with the decorated LSCF cathode show markedly improved peak power densities (∼0.94 W cm−2 at 700 °C). Furthermore, the ORR kinetics of the modified LSCF cathode can be further enhanced by impregnating Ni(NO3)2·6H2O and Co(NO3)2·6H2O solution again. X-ray photoelectron spectroscopy analysis indicates that the homogeneous nanoparticles alter the distribution of Srsurface and Osurface. It is found that ‘Co’ decoration can effectively alleviate the surface aggregation of Sr and ‘Co’ and ‘Ni’ decoration play a pivotal role in the reactivation of electrode surface.

Pulmonary injury associated with spray of a water-based nano-sized waterproofing product: a case study

BackgroundIn most reported cases of lung trauma with water proofing products, volatile organic compounds (VOC) have a prominent role. Here we report on a case involving ten workers exposed to a sprayed product containing nanoparticles in a water solution with only a few percent VOC.Case presentationTen workers suffered from respiratory symptoms following spray impregnation of hardwood furniture using a waterproofing product that contained positively charged fluorinated acrylate copolymer solid cores with a median diameter of 70 nm (1.3 w%) in aqueous suspension with 3.3 w% VOC and 0.3 w% quaternary ammonium. The worker who applied one liter of the product in a wood workshop, using an air mix spray gun, did not report any health complaints. Another worker, who entered the workshop 3 h later and had rolled and smoked two cigarettes, was hospitalized with severe chemical pneumonitis. A chest X-ray (CXR) showed bilateral infiltrative impairment in the lower lobe regions. On the next day a second CXR showed increased patchiness marking in all fields. A high-resolution Computer Tomography (CT)-scan demonstrated extensive bilateral areas of ground-glass opacities predominantly in the lower regions of the upper lobes, the right middle lobe and the apical regions of the lower lobes, compatible with severe chemical pneumonitis. On the following morning, nine workers in an adjacent workplace in the same building, experienced dry cough, chest tightness and substernal pain upon physical exercise. Reconstruction of the spray application in a climate chamber confirmed trimethyl silanol, glycol ethers and fluoroalkenes in the gas phase. Immediately after the spray application, aerosols were observed at a maximum concentration of 6.3 × 104 cm−3. Mass concentrations were 0.095 and 10 mg/m3 in the size ranges 5.6-560 nm and 0.22-30 μm, respectively, decreasing to less than 10 μg/m3 in both size ranges after 15 h.ConclusionThe hospitalized worker had smoked cigarettes contaminated with fluoropolymers which is a plausible explanation for the lung trauma. Respiratory symptoms in the nine workers may be caused by inhalation of particles that became airborne by resuspension from surfaces when workers entered the adjacent workplace the next day. A contribution from VOC appears less likely because measurements and modelling showed that concentrations in the mg/m3 range could have occurred only if the building was assumed to be completely airtight.

Selective hydrogenation of propyne on a solid Pd/Al2O3 catalyst modified with ionic liquid layer (SCILL)

The successful application of solid catalyst with ionic liquid layer (SCILL) concept in the selective hydrogenation of propyne is presented in this work. A Pd-based SCILL catalyst was prepared by spray impregnation of commercial available Pd/Al2O3 egg-shell catalyst and characterized by nitrogen sorption. Catalytic testing showed that even small amounts of ionic liquid were sufficient to suppress the consecutive reaction of propane formation, while propene selectivity was increased up to 97%. C6 oligomer formation, which is known to induce deactivation of the catalyst, could be prevented by excess hydrogen in the feed.

Progress in the deactivation of metals contaminated FCC catalysts by a novel catalyst metallation method

The artificial deposition of contaminant metals on FCC catalysts by pore volume impregnation methods (Mitchell) followed by hydrothermal deactivation in small scale units are the most common techniques for the deactivation of FCC catalysts in the laboratory due to the simplicity and robustness of such methods. However, such methods do not match the deposition of the metals on the outer surface of the FCC catalyst particles as observed for equilibrium catalysts (FCC catalysts equilibrated in FCC units).A new method of catalyst metallation has been developed using a spray impregnation technique, where the contaminant metals vanadium and nickel are deposited on the outer surface area of the FCC catalyst particles. Using this novel technique nickel remains primarily on the surface of the particles under severe hydrothermal conditions whilst vanadium migrates into the bulk of the particles and from particle to particle as observed in equilibrium catalysts. This dispersion of the contaminant metals occurs simultaneously with zeolite degradation and thus leads to different effects on the physical and catalytic properties of FCC catalysts compared to a Mitchell-type method where the contaminant metals already penetrate the FCC catalyst particles during the impregnation step. Such differences in physical and catalytic properties are shown by numerous examples. It is also demonstrated that the hydrothermal deactivation of catalysts metallated by the spray impregnation method results in catalyst properties being closer to those of equilibrium catalysts than the deactivation after metallation by the Mitchell method. Hence the catalytic testing of spray impregnated and deactivated samples provides more realistic results than the testing of Mitchell impregnated catalysts.

Thermoset lactic acid‐based resin as a matrix for flax fibers

AbstractThermoset composites were produced from flax fibers and a novel lactic acid (LA)‐based thermoset resin. This resin is based on methacrylated, star‐shaped oligomers of LA. The main purpose of this work was to evaluate whether this resin can be used to produce structural composites from flax fibers. Composites were prepared by spray impregnation followed by compression molding at elevated temperature. The tests showed that composites can be produced with as much as 70 wt% fiber. The composites were evaluated by tensile testing, flexural testing, charpy impact test, dynamic mechanical thermal analysis (DMTA), and low‐vacuum scanning electron microscopy. The ageing properties in high humid conditions were evaluated, the Young's modulus ranged from 3 GPa to 9 GPa in the best case. This work shows that structural composites can be produced from renewable material. It is clear from the results that these composites have properties that make them suitable for furniture, panels, or automotive parts. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation of thermoset composites from natural fibres and acrylate modified soybean oil resins

AbstractStructural composites with a high content of renewable material were produced from natural fibres and an acrylated epoxidized soybean oil resin. Composites were prepared by spray impregnation followed by compression moulding at elevated temperature. The resulting composites had good mechanical properties in terms of tensile strength and flexural strength. Tensile testing as well as dynamical mechanical thermal analysis showed that increasing the fibre content, increased the mechanical properties. The resin can be reinforced with up to 70 wt % fibre without sacrifice in processability. The tensile modulus ranged between 5.8 and 9.7 GPa depending on the type of fibre mat. The study of the adhesion by low vacuum scanning electron microscopy shows that the fibres are well impregnated in the matrix. The aging properties were finally evaluated. This study shows that composites with a very high content of renewable constituents can be produced from soy bean oil resins and natural fibres. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Characteristics of blueing as an alternative chemical conversion treatment on carbon steel

Alternative pretreatments are proposed in order to avoid the environmental aggressive impact produced by using surface finishing processes based on Cr(VI) compounds. In this work, blueing method is proposed as chemical conversion treatments (CCTs) in AISI 1010 commercial steel. CCTs were carried out by the so-called “Swiss blueing” method using a solution with 20 g HNO 3 + 5 g CH 3CH 2OH + 5 g CuSO 4·5H 2O + 160 g FeCl 3 dissolved in water (1:1). This solution was added onto steel sheets using spray impregnation technique. Anticorrosion protection and adhesion properties were evaluated using polarization resistance (Rp), ac impedance and pull-off test, respectively. The thickness, morphology and microstructure of the protective films have been examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Although, no-treated specimens showed the highest polarization resistance (Rp) and impedance values, the oxide compounds are porous and unstable, while samples with the CCTs increased anticorrosive protection and favoured a strong adhesion between substrate and top coating. Continuous immersion values obtained by ac impedance showed remarkable variations in the coating resistance. SEM micrographs indicate that chemical treatment increased the surface porosity–roughness. XRD patterns showed some iron oxide compounds: mainly magnetite, and a small quantity of hematite, which have influenced the electrochemical behavior and adhesion. Pull-off tests showed good adhesion in the previously treated samples. These results indicate that obtained roughness with one CCTs using “Swiss blueing” method increased anticorrosion protection and adhesion properties.

An electrostatic powder spray process for manufacturing thermoplastic composites

AbstractManufacture of thermoplastic composites is expensive because of the difficulty of impregnating the resin into the fibers. Powder processing shows great promise as an impregnation technique for cost‐effective manufacturing. This paper discusses an electrostatic powder spray impregnation technique that uses glass fibers. A geodesic fiber spreader is used to spread the fibers locally in the region of maximum powder deposition. A negative corona electrostatic spray gun is employed to charge and direct the powder for coating both sides of the spread fiber tow. The process has been used to impregnate glass fibers with poly(aryl ether ketone ketone) powder. The effect of the powder mass flow, corona voltage, and fiber tow velocity on powder deposition has been investigated. Particle image velocimetry is utilized to determine particle velocities. Compression molded panels have been produced and tested in three point bending.