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Xiao F.,Northeastern University China | Xiao F.,Shenyang research institute of nonferrous metals | Xiao F.,Henan University of Science and Technology | Li Y.,Northeastern University China | And 5 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2016

An activated carbon-supported palladium catalyst for hydropurification of crude terephthalic acid was prepared by coating coconut activated carbon with Pd nanoparticles synthesized from colloid solution containing ternary surfactants. The performance and microstructure of catalysts were investigated by means of scanning electron microscope, high resolution transmission electron microscope, H2 chemisorption and high performance liquid chromatography. The results show that the Pd particles in colloidal dispersion have a narrow size distribution and the average size is about 6.45 nm. The conversion rate of 4-carboxy benzaldehyde nearly reaches 100% under reaction temperature of 278 °C, H2 partial pressure of 0.5 MPa and reaction time of 1 h. The catalyst remains nearly stable after five consecutive hydropurification tests. When the concentration of these surfactants is 0.67 g/L, the catalytic performance of catalyst remains relatively high value. The ternary surfactants of Brij 35-Tween 80-CTAB provides a dense micellar layer which warps and minimizes the colloids particles and as a result the catalytic activity and stability of catalysts are increased. © 2016 Elsevier B.V. Source


Xiao F.,Shenyang research institute of nonferrous metals | Xiao F.,Henan University | Xiao F.,Northeastern University China | Ren Y.,Henan University | And 2 more authors.
Petroleum Processing and Petrochemicals | Year: 2013

A commercial coconut activated carbon was firstly pretreated by HCI with different concentrations. Then the Pd/C catalyst used for purification of terephthalic acid was prepared using immersion method based on the pretreated carbon. By means of SEM, EDS, TEM, XRD and BET techniques, the impact of HC1 pretreatment on microstructure and activity of the catalysts was investigated, and the relationship between HCI concentration and catalyst activity was explored. Test results show that the catalytic activity first increases and then decreases with the increase of HCI concentration and the maximum activity was obtained at the HCI concentration of 0.6 mol/L. SEM and adsorption desorption tests show that the pretreatment of HC1 can increase the average pore diameter and the mesopore volume of activated carbon. The EDS result indicates that the content of Pd maintains nearly constant, while some O element and trace impurity of Si and Cl appear on the carbon surface after HCI pretreatment. The changes of the surface morphology of HCI pretreated active carbon are not found. Owing to the increase of pore diameter and mesopore volume, the effective surface area of carbon for loading Pd component is increased, which is beneficial to the dispersity of Pd, and to the catalytic activity of Pd/C catalyst. Source


Xiao F.,Shenyang research institute of nonferrous metals | Xiao F.,Northeastern University China | Xiao F.,Henan University of Science and Technology | Li Y.,Shenyang research institute of nonferrous metals | And 4 more authors.
Advanced Materials Research | Year: 2013

The traditional method of preparing 0.5 wt.% nano Pd/C catalysts used for pure terephthalic acid(PTA) refining is the precipitate-reduction method, and this paper proposed the sol-gel method, in which the palladium colloid was firstly prepared, and followed by the load process onto the activated carbon. The activity and microstructure of catalysts were investigated by means of SEM, TEM, EDS, XRD and HPLC. It was found that the activity of catalyst with the sol-gel method was much higher than that with precipitate-reduction method. The preparation technology has less effects on the micostructure of Pd/C catalysts, while the palladium particles of catalyst obtained with sol-gel method are much finer and the relatively palladium content is much higher.These two factors contribute to the higher activity of Pd/C catalyst. © (2013) Trans Tech Publications, Switzerland. Source


Dai S.-J.,University Of Science And Technology Liaoning | Dai S.-J.,Hebei United University | Liu Y.,Shenyang research institute of nonferrous metals
Advanced Materials Research | Year: 2011

The N2H4-KHB reduction then CH3OH watering and H2 reduction system was used to make superfine nickel powder by using nickel sulfate as material.The superfine nickel powder of the specific surface area of the nickel powde being 4.24m2/g, spheric shape with grain size 0.5-0.9μm,nickel content being over 99.5%,The toll nichel recovery being over 99.5% was made on the condition of reaction temperature 60°C, reaction time 150-180min,pH 8.0-8.5,[Ni]=1.25M,N2H 4/Ni=1.35(mol ratio) ,sodium hexametaphosphate of 1.5%0 as additive, the dosage of KHB of 8.37×10-3g/g Ni and washing by carbinol,reducing by H2. © (2011) Trans Tech Publications. Source


Xiao F.,Shenyang research institute of nonferrous metals | Xiao F.,Henan University of Science and Technology | Xiao F.,Northeastern University China | Li Y.,Shenyang research institute of nonferrous metals | And 4 more authors.
Advanced Materials Research | Year: 2013

The 0.5 wt.% Pd/C catalysts used for purification of terephthalic acid(TA) were prepared, and the effects of dodecyltrimethylammonium bromide(DTAB) concentration on activity and microstructure of catalysts were investigated by means of SEM, TEM, XRD,HPLC,specific surface area(BET) and porosity test. The results show that DTAB can increase the activity of Pd/C catalysts, and the catalytic activity increases with the increase in DTAB concentration and nearly remains constant with further increase after it exceeds 0.5 wt.%. DTAB can clean the surface of activated carbon and diminish the palladium size of Pd/C catalysts. The addition of DTAB has effects in crystal structure of nano Pd/C catalysts, and the Pd crystal planes of (111) and (200) was replaced by a broad reflections after DTAB added. DTAB tends to form various meta-stable structures(spherical or cylindrical)at the solid-liquid interface that helps finer grain for mation and hinders subsequent coarsening of the palladium particles. © (2013) Trans Tech Publications, Switzerland. Source

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