No abstract

The pyrolysis behavior of Ni─Ca-loaded Yunnan brown coals (Shi Caoxing [SCX] and Guo Jiashan [GJS]) was studied in a fixed-bed reactor to investigate the effects of Ni, Ca, and Ni─Ca loading on the yields of the obtained liquids and light aromatic hydrocarbons. Structural variations of the prepared coal chars were characterized by the scanning electron microscope-energy dispersion X-ray, Fourier-transform infrared spectroscopy, X-ray diffractometer, Brunauer-Emmett-Teller analysis, and elemental analysis. The effects of the Ni, Ca, and Ni─Ca loadings on the tar yield and upgradation of pyrolysis tar were evaluated. The results revealed that the use of the Ni─Ca catalyst affords improved yields of the liquid products and tar. Furthermore, the light hydrocarbon liquids contents in the coal tar was improved with the use of the Ni─Ca catalyst. The heavy components and polycyclic aromatic hydrocarbons in the coal tar could be easy to convert into light hydrocarbon liquids (phenol, cresol, xylenols, and naphthalene) with the SCX brown coal pyrolysis. In contrast, the catalytic pyrolysis of GJS brown coal was inhibited by the Ni─Ca catalyst. The study revealed that the catalytic activity of the Ni─Ca catalyst greatly depends on the type of the coal substrate and was promoted or inhibited depending on the type of the brown coal. Highlights1. The content of light aromatic hydrocarbons is improved by Ni─Ca catalyst.2. The Ca promoter reacted with ash (S and Al) to form CaSO 4 , and CaAl 4 O 7 compounds.3. Phenols are the main components in the light aromatic hydrocarbons. 4. The catalytic activity of the Ni─Ca catalyst promoted or inhibited by coal rank.

Novel rod like phenylene thiophene based polyhydroxy amphiphiles, derivatives of gallic acid combining three hydrophilic 2,3-dihydroxypropyloxy groups and one alkyl chain via central aromatic linking units, have been synthesized by using Ni(II), Pd(0) catalyzed coupling reaction as key steps. The mesophase behavior of such compounds was investigated by POM and DSC. Thereby the influence of the position of the alkyl chains on the mesophase behavior was discussed. All such compounds exhibit smectic A phases. As the alkyl chain moving from the terminal position to the lateral position near the central of the rigid core, the stability of the smectic A phase would be decreased.