Unravelling the Anomalous Coking Resistance over Boron Nitride-Supported Ni Catalysts for Dry Reforming of Methane

Metal oxides have been used as the supports for heterogeneous catalysis formany years,but they still suffer from coking in some high-temperature applications.The main reasons for coking are the uncontrollable dissociation of C-H and the overbalance between carbon deposition and removal.Herein,we find a boron nitride(BN)-immobilized Ni catalyst shows unprecedented coking resistance in dry reforming of methane via the incomplete decomposition of methane.Unlike the Ni-based catalysts supported by traditional metal oxides,BN-supported Ni accelerates the first C-H dissociation while inhibiting the breaking of the final C-H bond;hence,the suppression of the complete decomposition of methane thoroughly addresses the coking issue.This work reveals the fundamental reason for the coking resistance over BN-supported Ni catalysts is selective activation of the C-H bond,which can provide an inspiring idea for other applications.

Er-modified MnO_(x) for selective catalytic reduction of NO_(x) with NH_(3) at low temperature:Promoting effect of erbium on catalytic performance

Various Er modified MnO_(x) catalysts were synthesized using co-precipitation approach and tested in the selective catalytic reduction of NO_(x) by ammonia(NH_(3)-SCR).Catalysts were analyzed with various characterization techniques,and it is found that the doping of Er can enormously enhance the catalytic performance of MnO_(x)catalyst.MnEr_(0.1)demonstrates advantageous catalytic performance in the NH_(3)-SCR reaction owing to rich surface acidic sites,high surface content of Mn^(4+),superior redox capacity,and enhanced surface-adsorbed oxygen.From diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)analysis,it is suggested that the MnEr0.1catalyst follows mainly Eley-Rideal mechanism while MnO_(x) is dominated by Langmuir-Hinshelwood mechanism.

Sm-MnO_(x)catalysts for low-temperature selective catalytic reduction of NO_(x)with NH_(3):Effect of precipitation agent

A series of Sm-Mn mixed oxide catalysts were prepared via precipitation using various precipitants,namely Na_(2)CO_(3)(NH_(4))_(2)CO_(3),and NH_(3)·H_(2)O,and evaluated for the selective catalytic reduction(SCR)of NO_(x)with NH_(3)at low temperatures.Various characterisation techniques were used to determine the physicochemical properties of the catalysts,and it is found that their catalytic performance is greatly influenced by the nature of the precipitation agent used.It is found that Sm_(0.1)Mn-Na_(2)CO_(3)and Sm_(0.1)Mn-(NH_(4))_(2)CO_(3)exhibit superior catalytic performance in the SCR reaction to that of Sm_(0.1)Mn-NH_(3)·H_(2)O due to an abundance of surface acid sites,high surface concentration of Mn^(4+),and high NO oxidation capacity.From in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFT)analysis,we conclude that the Sm-Mn catalysts follow both Eley-Rideal and Langmuir-Hinshelwood mechanisms,and that the Eley-Rideal mechanism is dominant at elevated temperatures.