Development of monolith with a carbon-nanofiber-washcoat as a structured catalyst support in liquid phase

Washcoats with improved mass transfer properties are necessary to circumvent concentration gradients in case of fast reactions in liquid phase, e.g. nitrate hydrogenation. A highly porous, high surface area (180 m2/g) and thin washcoat of carbon fibers, was produced on a monolith support by methane decomposition over small nickel particles. Carbon fibers form a homogeneous layer less then 1 ¿m thin, covering the surface of the channels in the monolith. The fibers penetrated into the cordierite, which is suggested to cause a remarkable stability of the fibers against ultrasound maltreatment. The texture of the fibers is independent of both the thickness of the ¿-alumina washcoat as well as the time to grow carbon fibers

Thermodynamics and Kinetics of Inhibition of Aluminum in Hydrochloric Acid by Date Palm Leaf Extract

The corrosion behavior of commercial aluminum in HCl was investigated by gravimetric method in absence and presence of date palm leaf extract (DPLE) as inhibitor. Corrosion rates in absence of extract ranged from 2.4-8.0 mg/cm2/h in the temperature range 20- 50\ubaC but decreased down to 0.30-2.6 mg/cm2/h in presence of the inhibitor. Hot-water extract of date palm leaves has shown inhibition efficiency (IE) of 40- 88% at the tested conditions. IE was found to increase with increasing inhibitor concentration from 0.2 to 0.6 g/L and decrease as temperature increased. Data showed that Langmuir adsorption isotherm represents surface coverage versus extract concentration data indicating that inhibition is due to monolayer adsorption of extract components on aluminum surface. Low activation energy and enthalpy values support physical adsorption mechanism. SEM-EDS microanalysis of aluminum surface supported the inhibitive effect of the extract at the metal surface

Application of full factorial design to optimize phosphogypsum beneficiation process (P 2 O 5 Reduction) by using sulfuric and nitric acid solutions

Abstract Inventing new ways to recycle and reuse the accumulated by-products is the most pressing and daunting challenge that face future engineers. Millions of tons of phosphogypsum (PG) is stacked worldwide every year and is progressively considered as an asset more than an environmental burden. Jordan cement industry is largely expanded in the last ten years and is considered as an opening to reuse the huge amount of Jordanian PG that is stacked every year. The impurities that PG contains hinder its use as an additive to the cement industry which is pushing towards developing a low cost and effective process to clean PG. Many researches used a number of physical, chemical and thermal methods to reduce P 2 O 5 content in PG, but all of these studies are invariant, did not go deep in understanding the process of washing/leaching of P 2 O 5 and is not oriented towards developing a process. In this study, a multivariate 2 4 full factorial methodologies is designed to study the effect of particle size, acid concentration, loading and number of washing on the P 2 O 5 washing/leaching process using sulfuric and nitric acid solution

Performance of chemically modified Tripoli in catalytic pyrolysis of date kernels

The use of natural minerals as catalysts in pyrolysis enhances the products’ yield and quality. However, natural minerals may lack the proper active sites to effectively catalyze the pyrolytic reactions. This paper addresses the performance of iron-chemically modified Jordanian Tripoli catalysts in the catalytic pyrolysis of date kernels. The Fe-chemically modified Tripoli catalyst was prepared by impregnation method at three different loadings (0.046, 1.788, 3.530 wt %). The effect of three different process variables, namely: pyrolysis temperature, heating rate and iron-loading on the performance of date kernels pyrolysis were investigated. Full factorial design methodology is employed to study the main effects of process variables and possible interaction effects among the process variables on the yields of the catalytic pyrolysis products. The maximum gas yield (197.8 ml/g-feed) was obtained at a pyrolysis temperature of 600 °C, heating rate of 20 °C/min and 3.530 wt% Fe-loading. The maximum bio-oil yield (42.88 wt%) was obtained at a pyrolysis temperature of 500 °C, heating rate of 60 °C/min and 1.788 wt% Fe-loading. The maximum bio-char yield (38.72 wt%) was obtained at a pyrolysis temperature of 400 °C, heating rate of 20 °C/min and catalytic pyrolysis using natural Tripoli. First order egression models are proposed to predict the product yields. The main implication of this study is that Fe-loaded Tripoli has effectively enhanced the quality of bio-oil

Mechanistic aspects of the formation of carbon-nanofibers on the surface of Ni foam: A new microstructured catalyst support

This paper describes the catalytic formation of a layer of carbon nanofibers (CNFs) on Ni foam, resulting in a new catalytic route for preparing thin, highly macroporous layers. The effect of morphology and surface properties (i.e., grain size and presence of NiO) on the rate formation and properties of CNFs is explored. The formation of CNFs on polycrystalline Ni starts with the formation of metastable Ni3C, which later decomposes into Ni and C. As a result, Ni nanoparticles are created with a suitable size (20–70 nm) to catalyze the formation of CNFs. The formation of CNFs on polycrystalline Ni reveals an inhibition time in accordance with the formation and decomposition of Ni3C resulting in Ni nanoparticles necessary for the growth of CNFs. Grain boundaries in the parent Ni material appear to enhance this process. The presence of NiO increases the formation rate of CNFs by one order of magnitude. NiO is reduced in situ, and Ni nanoparticles are formed directly, as opposed to sluggish formation of Ni nanoparticles via decomposition of Ni3C particles formed from relatively large (1–10 μm) Ni crystals

Growing a carbon nano-fiber layer on a monolith support; effect of nickel loading and growth conditions

This work describes how a new, extremely porous, hairy layer of carbon nano-fibers (CNFs) can be prepared on the surface of porous inorganic bodies, e.g. wash-coated monoliths. CNFs were prepared catalytically by methane and ethene decomposition over a Ni catalyst. The influence of the Ni particle size and growth conditions on the properties of the resulting material is reported. It turns out that the thickness of the CNF layer at the outermost surface (ca. 1 mm) as well as the diameter of the fibers increases with mean Ni particle size. The structure of this layer resembles the inverse structure of a traditional inorganic support material, combining high surface area, high porosity and low tortousity. Growing CNFs using methane leads to immediate fragmentation and doubling of the thickness of the washcoat which is independent of the amount of CNFs, forming a macro-porous composite layer of entangled alumina particles and CNFs with a typical diameter of 10¿30 nm. Immediate fragmentation is due to the fact that some of the fibers are too thick for the pores in the washcoat. The total porosity decreases with the amount of CNFs whereas the surface area per gram of monolith increases. Large Ni particles are able to grow CNFs for longer times, resulting in detachment of the washcoat from the cordierite, which is caused by extensive growth of CNFs out of the washcoat. Furthermore, extended growth of CNFs inside the cordierite body causes disintegration of the monolith body when macro-pores are locally overfilled with CNFs. Methane is preferred over ethene for growing CNFs because ethene grows CNFs rapidly even on relatively large Ni particles, resulting in thick fibers up to 70 nm in the macro-porous cordierite, destroying the monolith. Controlling both the Ni particle size and Ni distribution as well as choosing the right activity of the hydrocarbon are essential to grow CNF washcoats without damaging the monolith structure