Role of in-situ Formed Nonoxides Bonded Phases in Property Improvement of Alumina ULC Castables

In order to enhance performance of pre-cast shapes of alumina based castables, the present work explored the approach of forming in-situ bonding phases by incorporating Si powders and then heating in carbon, embedded atmosphere. Using tabular alumina as aggregates, tabular alumina, SiC powders, Si powders, calcium aluminate cenwnt, microsilica and ultrafine α-A12 03 powders as matrix, alumina based ultra low cement （ULC） castables were prepared. Influences of Si powder addition at O, 4% , 6% , 8% alul 10% （in nutss ） on regular properties, cold modulus of rupture （CMOR）, hot modulus of rupture （HMOR）, thermal shock resistance （TSR） and microstructure of the castables after carbonization were investigated. After incorporation of Si powders and carbon embedded heating, the in-situ mullite and nonoxide phases such as SiAION and SiC can be fornwd by oxidation, nitridation or carbomlzation reaction. HMOR and TSR of the castables with in-situ nonoxides bonding are obviously improted. After carbon embedded heating, the HMOR at 1 400 ℃ increases from 1.6 MPa to 8. 3 MPa, and the residual CMOR ratio after thermal shock increases from 64. 9% to 137. 9% when Si addition increases from 0 to 10%.

Strong metal-support interactions between gold nanoparticles and nonoxides

With the support of the National Natural Science Foundation of China,Prof.Zhang Tao(张涛)and Prof.Wang Junhu’s group at the Laboratory of Catalysts and New Materials for Aerospace,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,recently discovered a new type of strong metalsupport interaction(SMSI)between gold nanoparticles(NPs)and nonoxides,which was published in

Simultaneous generation of electricity, ethylene and decomposition of nitrous oxide via protonic ceramic fuel cell membrane reactor

Ethylene,one of the most widely produced building blocks in the petrochemical industry,has received intense attention.Ethylene production,using electrochemical hydrogen pump-facilitated nonoxidative dehydrogenation of ethane(NDE)to ethylene,is an emerging and promising route,promoting the transformation of the ethylene industry from energy-intensive steam cracking process to new electrochemical membrane reactor technology.In this work,the NDE reaction is incorporated into a BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)electrolyte-supported protonic ceramic fuel cell membrane reactor to co-generate electricity and ethylene,utilizing the Nb and Cu doped perovskite oxide Pr_(0.6)Sr_(0.4)Fe_(0.8)Nb_(0.1)Cu_(0.1)O_(3-δ)(PSFNCu)as anode catalytic layer.Due to the doping of Nb and Cu,PSFNCu was endowed with high reduction tolerance and rich oxygen vacancies,showing excellent NDE catalytic performance.The maximum power density of the assembled reactor reaches 200 mW cm^(-2)at 750℃,with high ethane conversion(44.9%)and ethylene selectivity(92.7%).Moreover,the nitrous oxide decomposition was first coupled in the protonic ceramic fuel cell membrane reactor to consume the permeated protons.As a result,the generation of electricity,ethylene and decomposition of nitrous oxide can be simultaneously obtained by a single reactor.Specifically,the maximum power density of the cell reaches 208 mW cm^(-2)at 750℃,with high ethane conversion(45.2%),ethylene selectivity(92.5%),and nitrous oxide conversion(19,0%).This multi-win technology is promising for not only the production of chemicals and energy but also greenhouse gas reduction.

Looking Ahead——A New Generation of High Performance Refractory Ceramics

It is expected that in the new century, to cope with developments of new high temperature technologies , a new generation of high performance refractory ceramics will e-merge and flourish which should include the following (1) oxide and nonoxide composites characterized by a unique combination of high hot strength , high thermal shock resistance and high corrosion resistance ; (2) free CaO bearing basic refractories capable of purifying molten metal for improving cleanliness and of absorbing contaminants from waste gases for reducing environmental pollution ; (3) free flowing zero cement castables with improved thermome-chanical properties , thermal shock resistance and corrosion resistance and gradient castables with varying matrix composition and varying texture.

Photocatalytic nonoxidative coupling of methane to ethylene over carbon-doped ZnO/Au catalysts

A photocatalytic nonoxidative coupling of methane to multi-carbon compounds remains a huge challenge due to its high dissociation energy of C–H bonds and sluggish charge carrier dynamics.Au-modified carbon-doped ZnO(C-ZnO/Au)photocatalyst is constructed by an interfacial modification-assisted self-assembly approach for efficient photocatalytic nonoxidative coupling of methane to ethylene and hydrogen(2CH_4=C_2H_4+2H_2).Benefitting from the presence of C-ZnO/Au interfaces,the catalyst not only weakens the excitonic confinement to improve the photogenerated charge carrier separation,but also enhances the stability of lattice oxygen to suppress C_2H_4 overoxidation.Moreover,this hybrid catalyst also accelerates the generation of Zn~+–O~–pairs to activate C–H bonds,stabilizes the important reaction intermediate(*OCH_3)to achieve the C–C coupling,and promotes the generation of low-valence Zn to accelerate the dehydrogenation of the*OC_2H_5 into C_2H_4.Therefore,a stable photocatalytic methane conversion performance can be achieved over C-ZnO/Au heterojunctions with a stoichiometric generation of the oxidation product(C_2H_4,45.85μmol g~(-1)h~(-1))and reduction product(H_2,88.07μmol g~(-1)h~(-1)).This work provides deep insights into the elemental doping and oxide/Au interfaces for the enhanced photocatalytic activity and product selectivity under mild conditions in the absence of extra oxidants.