Styrene (ST) is an industrially important commodity chemical, and design of a suitable catalyst, which provides high ethyl benzene (EB) conversion and styrene selectivity at lower temperature with sustainable activity, is one of the major challenges in the field of heterogeneous catalysis. Manganese incorporated in titania (Mn x Ti 1Àx O 2 ) anatase lattice, prepared via the solution combustion method, was evaluated for oxidative dehydrogenation (ODH) of EB with O 2 or air. Mn x Ti 1Àx O 2 catalysts were characterized by different physiochemical methods. Up to 15% Mn could be introduced into the TiO 2 lattice. TEM and XRD indicate disordered mesoporosity, further confirmed by adsorption isotherm analysis. Mn x Ti 1Àx O 2 catalysts were evaluated for ST synthesis from EB using air or oxygen as oxidant between 440 and 570 C. Reaction conditions have been varied systematically, such as catalyst composition, and EB/air/O 2 flow. Mn x Ti 1Àx O 2 shows sustainable 55% styrene yield for 45 h without deactivation under optimum conditions. A thorough analysis of spent catalysts demonstrates the conversion of initial anatase phase Mn x Ti 1Àx O 2 to Mn 3 O 4 supported on the rutile (R) phase of TiO 2 . The above change occurs in the first few hours of reaction and the Mn 3 O 4 on R-TiO 2 phase is the active phase of the catalyst and responsible for sustainable activity for longer duration.
The
performance of a dye-sensitized solar cell (DSSC) is strongly
affected by optical, structural, and electronic features of a photoanode.
In this article, meso-TiO
2–
X
was
prepared by a solution combustion method and hydrogenation at high
pressure. The properties of DSSCs with meso-TiO
2–
X
photoanodes were investigated by photocurrent–voltage,
incident photon-to-current conversion efficiency, and electrochemical
impedance spectroscopy (EIS) measurements. The meso-TiO
2–
X
materials exhibit new electronic states and aided
to absorb in the visible region because of the narrow band gap. Facile
charge transfer from the N719 dye to the TiO
2
photoanode
was assisted by low-lying mid-gap states. Electrically integrated
nanoparticles, with a small-channel mesoporous framework, facilitates
fast charge transport across the material. Furthermore, EIS has shown
that chemical capacitance, recombination resistance, and electron
lifetime were affected by hydrogenation, thus indicating an effect
on the photoanode material charge dynamics of DSSCs. An η of
7.2% under AM 1.5G illumination is obtained and an improvement by
75.6% over Degussa P25 titania. This is attributed to improved light
harvesting and charge collection by the meso-TiO
2–
X
photoanode obtained via simple combustion synthesis.
This paper presents the signal processing approach to detect and characterize the physical events that occur in power system using PMUs signals. A small window is applied so that the extracted spectral features belong to a stationary signal. This is based on applying empirical mode decomposition, followed by square root of spectral kurtosis (SRSK) for computation of statistical indices to indicate the event occurrence. Subsequently, features from these events are extracted using mel frequency cepstral coefficients on SRSK.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.