No abstract

Lignin is a potential renewable material for the production of bio-sourced aromatic chemicals. We present the first hydrotreatment of lignin pyrolysis vapors, before any condensation, using inexpensive and sustainable iron-silica (Fe/SiO2 ) and iron-activated carbon (Fe/AC) catalysts. Lignin pyrolysis was conducted in a tubular reactor and vapors were injected in a fixed bed of catalysts (673 K, 1 bar) with stacks to investigate the profile of coke deposit. More than 170 GC-analyzable compounds were identified by GCxGC (heart cutting)/flame ionization detector mass spectrometry. Lignin oligomers were analyzed by very high resolution mass spectrometry, called the "petroleomic" method. They are trapped by the catalytic fixed bed and, in particular, by the AC. The catalysts showed a good selectivity for the hydrodeoxygenation of real lignin vapors to benzene, toluene, xylenes, phenol, cresols, and alkyl phenols. The spent catalysts were characterized by temperature-programmed oxidation, transmission electron microscopy (TEM), and N2 sorption. Micropores in the Fe/AC catalyst are completely plugged by coke deposits, whereas the mesoporous structure of Fe/SiO2 is unaffected. TEM images reveal two different types of coke deposit: 1) catalytic coke deposited in the vicinity of iron particles and 2) thermal coke (carbonaceous particles ≈1 μm in diameter) formed from the gas-phase growth of lignin oligomers.

The promising and extraordinary properties of graphene have attracted significant interest, making graphene an alternative to replace many traditional materials for many applications, particularly in conductive ink for the fabrication of flexible electronics. For the past 10 years, numerous studies have been reported on the synthesis of graphene conductive ink for printing on flexible substrates for various electronic applications. The development of graphene-based ink is reviewed, with the main focus on the types of graphenelike materials in conductive inks, and the compositions and important properties of those inks. Another intention behind this review is to compare the pros and cons of graphene-based ink with those using other common conductive materials, such as gold nanoparticles, silver nanoparticles, copper nanoparticles, conductive polymers and carbon nanotubes. Recent works on graphene hybrid-based ink containing other metallic nanoparticles as an alternative way to improve the electrical properties of the conductive inks are also reported. Brief comparisons between inkjet printing and other printing techniques for the fabrication of flexible electronics are discussed.