Saifu Long,Shijian Zhou,Fu Yang,Kangchao Lu,Tao Xi,Yan Kong
Surface exposed catalytic active species are thought to be responsible for overall catalytic activity and selectivity. In this paper, controllable contents of iron oxides were in situ introduced into the inner surface of anionic surfactant-templated mesoporous silica (AMS) by the metal-modified anionic surfactant templating route, in which anionic micelles decorated with different amounts of Fe2+ were direct utilized to assemble with organosilicate. The characterization results demonstrated that, after thermal treatments, Fe2O3 species were in situ formed and highly-dispersed in the channels of AMS, and the pore size was accordingly tailored to the microporous level (<2 nm). In each AMS catalyst, Fe2O3 showed better dispersion and stability compared with the post-impregnated method. Moreover, the catalytic performances of phenol hydroxylation on the as-synthesized catalysts were significantly enhanced, and the optimal catalyst (Fe/Si = 3.5 wt%) gave a phenol conversion of 44.3% with a selectivity of 82.6% to dihydroxybenzene. By comparison with some reference mesoporous silica catalysts (0.15Fe/MCM-41 and 0.15Fe/SBA-15), the iron-based micropore-enriched silica catalyst (Fe/AMS) gave an obviously higher selectivity to dihydroxybenzene. Finally, the optimal catalyst was examined for at least 5 runs in phenol hydroxylation.
N-doped porous carbons have been regarded as competitive candidates for CO 2 adsorption by virtue of tunable micropores and basic nitrogen sites. Herein, we synthesized the ultramicropore-enriched N-doped carbon by pyrolysis of polyethyleneimine-based polymer network which was formed by nucleophilic substitution reaction of polyethyleneimine and p-dichloroxylene. The precursor with evenly anchored amine groups on the surface and interior could not only serve as pore-forming agent by self-decomposition, but also generate abundant nitrogen sites to enhance the surface polarity. By adjusting carbonization temperatures (500, 600, 700 and 800 °C) and amounts of KOH activator, the texture properties and nitrogen contents of the N-doped porous carbons (denoted as CPDs) were tuned finely. Impressively, the CPD-600 pyrolyzed at 600 °C possessed large surface area (1638 m 2 /g), narrow-distributed ultramicropores (d < 0.7 nm) and high nitrogen content (6.16 wt%). The sufficient nitrogen species (especially pyrrolic-N) as the basic “CO 2 -philic” sites could strengthen the affinity of polar surfaces toward CO 2 molecules. Moreover, the well-developed ultramiropores offered restricted spaces that could capture CO 2 by superposition effect of Van der Waals’ force. These advantages endowed CPD-600 with high-performance of CO 2 uptake (4.92 mmol/g), CO 2 /N 2 (15/85, v/v) selectivity (31) and regenerability at 298 K and 1 bar. The rational design of polymer-derived porous carbons with tailoring structural and functional properties could be applied not only to CO 2 capture from gas mixtures but also to other advanced fields.
危险品化学品经营许可证（带存储）