Activity and basic properties of KOH/mordenite for transesterification of palm oil

The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 C and atmospheric pressure.The KOH/mordenite processed transesterification in the batch reactor gave the highest methyl ester yield of96.7%under optimum conditions,while a methyl ester content over 94.5%was obtained in the packed-bed reactor.This comparison indicates that transesterification in a batch-type reactor gives a higher methyl ester yield than that of a continuous-flow reactor.Dealumination was found in the calcined catalysts and had a significant effect on the physical structure and chemical composition of the catalysts.Leaching of the potassium species was negligible,whereas depositing and washing of the reacted mixture with acetone on the catalyst surface were observed by FTIR.

The Effect of Nb Loading on Catalytic Properties of Ni/Ce_(0.75)Zr_(0.25)O_2 Catalyst for Methane Partial Oxidation

In this study, the effect of Nb loading on the catalytic activity of Ce0.75Zr0.25O2-supported Ni catalysts was studied for methane partial oxidation. The catalysts were characterized by BET, H2 chemisorption, XRD, TPR, TEM and tested for methane partial oxidation to syngas in the temperature range of 400-800 ℃at atmospheric pressure. The results showed that the activity of methane partial oxidation on the catalysts was apparently dependent on Nb loading. It seemed that the addition of Nb lowered the catalytic activity for methane partial oxidation and increased the extent of carbon deposition. This might be due to the strong interaction between NiO and Nb-modified support and reduction of surface oxygen reducibility.

Lead zirconate(PbZrO_(3))embedded in natural rubber as electroactive elastomer composites

Perovskite lead zirconate(PbZrOz)was synthesized in an orthorhombic form at a temperature below the Curie temperature,Tc.The orthorhombic form is a noncentrosymmetric structure which is capable of spontaneous polarization.Fourier transform infrared(FTIR)spectra and X-ray diffraction(XRD)patterns confirm the siuccessful synthesis of the lead zirconate;and scanning electron microscopy(SEM)micrographs indicate that PbZrO_(3) particles are moderately dispersed in the natural rubber(NR)matrix.Without an electrical field,the particles merely act as a ferroelectric fller,which can absorb and store additional stress.Under an electrical field,particle induced dipole motents are generated,leading to interparticle interaction and a sub-stantial increase in the storage modulus.At a small amount of lead ziroonate part iculates present in the natural rubber matrix,at a volume fraction of 0.007306,the electrical conductivity increases dramatically by nearly two orders of magnitude at the electrical frequency of 500 kHz.

Effect of synthesis time on morphology of CeO2 nanoparticles and Au/CeO2 and their activity in oxidative steam reforming of methanol

Ceria(CeO2)supports,synthesized by hydrothermal treatment with different synthesis time(CeO2-X h,where X is the synthesis time in h)in the presence of the surfactant cetyltrimethyl ammonium bromide,were used as supports for gold(Au)catalysts.The synthesis time significantly affects the morphological structure and crystallite size of CeO2,where CeO2-2 h has the smallest crystallite size with coexisting nanorods and nanoparticles.Transmission electron microscopy analysis confirms the morphology of CeO2 with distinctive(110),(100)and(111)planes,in agreement with interplanar spacings of 0.19,0,27 and 0.31,respectively.However,the morphology of CeO2-8 h and CeO2-48 h is mainly a truncated octahedral with crystal planes(111)and(100)accompanied by an interplanar spacing of 0.31 and0.27 nm,respectively.The CeO2-X h supports and those with a 3 wt%Au loading(Au/CeO2-X h)were investigated in the oxidative steam reforming of methanol at temperatures between 200 and 400℃.The Au/CeO2-2 h gave the highest methanol conversion level and hydrogen yield at a low temperature of 250℃.This superior catalytic performance results from the good interaction between the metal and support and the well-distributed Au species on the CeO2 support.

Facile preparation of polybenzoxazine-based carbon microspheres with nitrogen functionalities:effects of mixed solvents on pore structure and supercapacitive performance

In this study,polybenzoxazine(PBZ)-based carbon microspheres were prepared via a facile method using a mixture of formaldehyde(F)and dimethylformamide(DMF)as the solvent.The PBZ microspheres were successfully obtained at the F/DMF weight ratios of 0.4 and 0.6.These microspheres exhibited high nitrogen contents after carbonization.The microstructures of all the samples showed an amorphous phase and a partial graphitic phase.The porous carbon with the F/DMF ratio of 0.4 showed significantly higher specific capacitance(275.1 F·g^-1)than the reference carbon(198.9 F·g^-1)at 0.05 A-g This can be attributed to the synergistic electrical double-layer capacitor and pseudo-capacitor behaviors of the porous carbon with the F/DMF ratio of 0.4.The presence of nitrogen/oxygen functionalities induced pseudo-capacitance in the microspheres,and hence increased their total specific capacitance.After activation with CO2,the specific surface area of the carbon microspheres with the F/DMF ratio of 0.4 increased from 349 to 859 m^2•g^-1 and the specific capacitance increased to 424.7 F·g^-1 This value is approximately two times higher than that of the reference carbon.The results indicated that the F/DMF ratio of 0.4 was suitable for preparing carbon microspheres with good supercapacitive performance.The nitrogen/oxygen functionalities and high specific surface area of the microspheres were responsible for their high capacitance.

Carbon dioxide adsorption/desorption performance of single-and blended-amines-impregnated MCM-41 mesoporous silica in post-combustion carbon capture

High-surface-area,hexagonal-structured mesoporous silica,MCM-41,was synthesized and wet impregnated with three different amines of 2-(ethylamino)ethanol(EAE),ethylenediamine(EDA),and tetraethylenepentamine(TEPA)for use as solid adsorbents in post-combustion CO_(2) capture application.The CO_(2) adsorption test was performed at 25℃and atmospheric pressure using 15/85 vol%of CO_(2)/N2 at a 20-mL/minute flow rate.Desorption was carried out at 100℃under 20 mL/minute of N2 flow.The results show that the capacity and rate of CO_(2) adsorption obtained from all the amine-modified adsorbents were significantly increased with increasing amine loading due to carbamate formation.Desorption efficiency and heat duty for regeneration were also affected by the amount of amine loading.The more stable the carbamate produced,the higher the energy was required.They exhibited the highest adsorption-desorption performance at 60 wt%amines used for impregnation.Blended EAE/TEPA at different weight ratios at a total concentration at 60 wt%amines was impregnated on MCM-41 adsorbent.Sorbent impregnated with 50%/10%of EAE/TEPA showed the best performance of 4.25 mmolCO_(2)/g at a high adsorption rate,a low heat duty of 12 kJ/mmolCO_(2) and with 9.4%reduction of regeneration efficiency after five repeated adsorption-desorption cycles.

Advancement and new perspectives of using formulated reactive amine blends for post-combustion carbon dioxide (CO_(2)) capture technologies

Chemical absorption using amine-based solvents have proven to be the most studied,as well as the most reliable and efficient technology for capturing carbon dioxide(CO_(2))from exhaust gas streams and synthesis gas in all combustion and industrial processes.The application of single amine-based solvents especially the very reactive monoethanolamine(MEA)is associated with a parasitic energy demand for solvent regeneration.Since regeneration energy accounts for up to threeequarters of the plant operating cost,efforts in its reduction have prompted the idea of using blended amine solvents.This review paper highlights the success achieved in blending amine solvents and the recent and future technologies aimed at increasing the overall volumetric mass transfer coefficient,absorption rate,cyclic capacity and greatly minimizing both degradation and the energy for solvent regeneration.The importance of amine biodegradability(BOD)and low ecotoxicity as well as low amine volatility is also highlighted.Costs and energy penalty indices that influences the capital and operating costs of CO_(2) capture process was also highlighted.A new experimental method for simultaneously estimating amine cost,degradation rate,regeneration energy and reclaiming energy is also proposed in this review paper.

Surface modification of polypropylene non-woven fibers with TiO_2 nanoparticles via layer-by-layer self assembly method:Preparation and photocatalytic activity

Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic acid）（PSS） and poly（diallyl-dimethylammonium chloride）（PDADMAC） to improve the anchoring of the Ti O2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic Ti O2 nanoparticles to construct Ti O2/PDADMAC bilayer in the Lb L fashion. The number of deposited Ti O2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust Ti O2 loading. The Lb L technique showed higher Ti O2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue（MB）. Results showed that the Ti O2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of Ti O2 powder dispersed in solution. The deposition of Ti O23 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr.Ti O2-Lb L constructions also preserved Ti O2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of Ti O2 particles from the substrate outer surface. However, even in the third cycle, the Ti O2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.

Methane partial oxidation over NiO-MgO/Ce0.75Zr0.25O2 catalysts

Methane partial oxidation （MPO） is considered as an alternative method to produce hydrogen because it is an exothermic reaction to afford a suitable H2/CO ratio of 2. However, carbon deposition on a catalyst is observed as a major cause of catalyst deactivation in MPO. In order to find suitable catalysts that prevent the carbon deposition, NiO-MgO/Ce0.75Zr0.2502 （CZO） supported catalysts were prepared via the co-impregnation （C） and sequential incipient wetness impregnation （S） methods. The amount of Ni loading was fixed at 15 wt-% whereas the amount of MgO loading was varied from 5 to 15 wt-%. The results revealed that the addition of MgO shifted the light-off temperatures to higher temperatures. This is because the Ni surface was partially covered with MgO, and the strong interaction between NiO and NiMgO2 over CZO support led to the difficulty in reducing NiO to active Ni~ and thus less catalytic activity. However, among the catalysts tested, the 15Ni5Mg/CZO （S） catalyst exhibited the best catalytic stability for MPO after 18 h on stream at 750℃. Moreover, this catalyst had a better resistance to carbon deposition due to its high metallic Ni dispersion at high temperature.

Investigation of adsorption/desorption performance by aminopropyltriethoxysilane grafted onto different mesoporous silica for post-combustion CO_(2) capture

Mesoporous silicas with hexagonal structure(MCM-41 and SBA-15)and cubical interconnected pore structure(KIT-6)were synthesized and modified with aminopropyltriethoxysilane(APTES)for using as adsorbents in carbon-dioxide(CO_(2))-adsorption application.The CO_(2)-adsorption experiment was carried out at room temperature and atmospheric pressure using 15%CO_(2) with a flow rate of 20 mL/min and the desorption experiment was carried out at 100℃ under N_(2) balance with a flow rate of 20 mL/min.The adsorption capacity and adsorption rate of all modified mesoporous silicas were enhanced due to the presence of primary amine in the structure,which was able to form a fast chemical reaction with CO_(2).All adsorbents showed good adsorption performance stability after using over five adsorption/desorption cycles.Due to the effect of the adsorbents’porous structure on the adsorption/desorption process,an adsorbent with sufficient pore-size diameter and pore volume together with interconnected pore,KIT-6,represents a promising adsorbent that gave the optimum adsorption/desorption performance among others.It showed reasonable adsorption capacity with a high rate of adsorption.In addition,it could also be regenerated with 99.72% efficiency using 12.07 kJ/mmol CO_(2) of heat duty for regeneration.

Enhancement of methanogenic activity by micronutrient control: Micronutrient availability in relation to sulfur transport

The main purpose of this research was to clarify the influence of the addition of iron(Fe)alone(0–100 mg/L)or 50 mg/L of Fe with 2 mg/L each of cobalt(Co),copper(Cu)and nickel(Ni)on the methanogenic activity of a mesophilic two-stage UASB system treating ethanol wastewater at a fixed chemical oxygen demand(COD)loading rate of 16 kg/m^(3)/day under a continuous mode of operation and steady state condition.The addition of Fe provided the dual benefits of a reduction in both the dissolved sulfide and the hydrogen sulfide(H_(2)S)content in produced gas,resulting inmarginally improved hydrogen(H_(2))and methane(CH_(4))productivities.When the Fe dosage was increased beyond the optimum value of 50 mg/L,the process performance drastically declined,as a consequence of the high total volatile fatty acid(VFA)concentrations that inhibited both the acidogens and methanogens predominantly present in the 1st and 2nd reactors,respectively.The chemical precipitation of iron sulfide was responsible for the reduction of produced H_(2)S in both the aqueous and gaseous phases as well as the minimization of added amounts of all other micronutrients to fulfil the sufficiency of all micronutrients for anaerobic digestion(AD).The addition of 2 mg/L each of Co,Cu and Ni together with 50 mg/L Fe resulted in the greatest enhancement in process performance,as indicated by the improved CH_(4) yield(mL/g COD applied)to about 42.3%,compared to that without micronutrient supplement.

Morphology dependent? Elucidating the catalyst structures of Ni/Ce_(0.75)Zr_(0.25)O_(2) in the steam reforming of acetic acid

In this work,the steam reforming of acetic acid was catalyzed by Ni-based catalysts supported on ceria-zirconia of different morphological structures(nanopolyhedra,nanorods,and nanocubes).The altered shapes led to the variation in catalyst properties,such as the exposed planes,ease of Ni reduction/oxidation,and carbon removal,which affected its catalytic performance.Additionally,it was found that the exposed planes present in cubic{100}and rod structures({100}and{110})enhanced the formation of Ni^(0) and subsequently promoted the reforming reaction.Moreover,oxygen vacancies and mobility properties of{100}and{110}exposed planes can promote the oxidation reaction of carbon,resulting in a stable catalyst for the reforming of acetic acid.The results also showed that the type of depositing carbons was influenced by the support morphology.All the catalysts showed a100% acetic acid conversion with the 15Ni/NC-Ce Zr(cubic structure)catalyst exhibited the highest hydrogen yield.