Experimental and Modeling Study on C_(2)H_(2)Oxidation and Aromatics Formation at 1.2 MPa

Oxidation of acetylene(C_(2)H_(2))has been investigated in a high-pressure jet-stirred reactor(HP-JSR)with equivalence ratiosΦ=0.5,1.0,2.0 and 3.0 in the temperature range of 650 K-900 K at 1.2 MPa.18 products and intermediates were analyzed qualitatively and quantitatively by gas chromatography(GC)and gas chromatography-mass spectrometry(GC-MS).Generally,withΦincreasing,the production of intermediates increases significantly.CH_(4),C_(2)H_(4),C_(2)H_(6),C_(3)H_(6)and C_(3)H_(8)were important intermediates,which were formed abundantly atΦ=3.0.Sufficient light hydrocarbon intermediates could be an important reason for significant formation of cyclopentadiene,benzene,toluene and styrene atΦ=3.0.A detailed kinetic mechanism consisting of 299 species and 2041 reactions has been developed with reasonable predictions against the present data and previous results obtained at 0.1 MPa.According to flux and sensitivity analysis,H and OH radicals play important roles in the consumption of C_(2)H_(2).The combinations among light hydrocarbons and their free radicals are the main generation pathways of aromatics.C_(3)H_(3),IC_(4)H_(5)and AC_(3)H_(5)are important precursors for the formation of aromatics.By comparing the results of atmospheric pressure and high pressure,it can be found that increasing the pressure is conducive to fuel consumption and aromatics generation.

Precipitation of metal oxide nanoparticles using a miniemulsion technique

A method to precipitate nanoparticles using a miniemulsion technique is described, in which miniemulsion droplets between 100 and 1000 nm in size serve as nanoreactors enabling both the control of particle formation and particle growth. The application of miniemulsion droplets to synthesise nanoparticles comprises three advantages： first, the size of the precipitated particles is limited by the reactant concentration within the emulsion droplet; second, particle agglomeration is prevented as nanoparticle collision outside the nanoreactor is avoided; and third, easy technical scale up can be realized by increasing emulsion volume and thus the number of nanoreactors, while local conditions within the reactors are not changed, The miniemulsion technique is an easy scalable process which allows defined synthesis of particles by precipitation reactions. The miniemulsion technique involves first the preparation of a stable water-in- oil miniemulsion by high pressure homogenisation. Whereas a water soluble reactant is provided within the aqueous droplets, another oilas well as water-soluble reactant can be introduced to the emulsion after homogenisation. The precipitation reaction is induced by the diffusion of the second reactant into the emulsion droplet. Together with this contribution, a method is described and discussed which uses a high pressure homogenisation process to produce stable water-in-oil miniemulsions serving as a reaction medium to precipitate metal oxides.