King Fahd University of Petroleum and Minerals

About: King Fahd University of Petroleum and Minerals is a education organization based out in Dhahran, Saudi Arabia. It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 7603 authors who have published 24030 publications receiving 443803 citations. The organization is also known as: College of Petroleum and Minerals.

The effect of sunlight induced surface defects on the photocatalytic activity of nanosized CeO2 for the degradation of phenol and its derivatives

Abstract: The photocatalytic activity of nanostructured CeO 2 was investigated for the degradation of phenol and its derivatives (2-chlorophenol, 2-bromophenol and 2-nitrophenol) in the exposure of complete spectrum and visible region (420–800 nm) of sunlight. The adopted experimental parameters imparted high crystallinity, phase purity, controlled morphology and uniform particle size of ∼11 nm to the synthesized CeO 2 . During the evaluation of the photocatalytic activity, the initial low degradation of the substrates till the 90 min of complete spectrum sunlight exposure followed by a piercing increase predicted the favorable photon induced surface changes in CeO 2 . The careful examination of the exposed and unexposed CeO 2 by spectroscopic techniques (diffuse reflectance (DR), photoluminescence (PL), ATR-FTIR and Raman spectroscopy) and electrochemical tools (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP)) revealed the vital role of photon induced surface phases for the improved spectral response and suppressed charge carries recombination process. Based on the appearance of additional weak reflection at 2 θ = 28.15° in the X-ray diffraction (XRD) pattern and inhalation of O 2 in the thermogravimetric analysis (TGA) of sunlight exposed samples revealed the prevalence of photon induced defects generated by the departure of surface oxygen from CeO 2 . The induction of defects composed of CeO 2-x states resulted in the improved activity of the exposed compared to unexposed CeO 2 in the visible spectrum (420–800 nm) of sunlight. The efficient degradation of 2-CP, 2-BP and 2-NP compared to a mild degradation for phenol, in the complete spectrum sunlight exposure, indicated the facilitating role of substituents attached to the aromatic system in the degradation process. The monitoring of the photocatalytic degradation process by HPLC and identification of intermediates by GC–MS analysis revealed the formation of aromatic intermediates in the degradation of phenol and 2-BP while no aromatic intermediate was identified in the degradation of 2-NP and 2-CP. The rapid disappearance of the total carbon and further oxidation of released anions supported the major role of superoxide anion radicals in the oxidation process. Both pure and sunlight exposed CeO 2 exhibited sustained photocatalytic activity in the repeated exposures.

Attenuation of P- and S-waves as a method of distinguishing gas and condensate from oil and water

Abstract: Compressional- and shear-wave attenuation data were calculated from sonic waveforms in three wells. The results show that at similar porosities and at in-situ conditions, gas and condensate sandstone reservoirs exhibit higher P-wave attenuation (lower P-wave quality factor, Q p ) than either fully-water or partially «oil+water» saturated sandstones. However, S-wave attenuation and quality factor Q S do not show such a strong dependence on pore fluids. Furthermore, Q P /Q S <1 indicates presence of gas or condensate, while Q P /Q S - I indicates «full water» or «oil+water» saturation. These field data are consistent with laboratory data and theoretical predictions by various researchers. The crossovers of P-Swave attenuation and Q P -Q S quality factors proved useful for distinguishing gas and condensate from oil and water reservoirs. They may be used in conjunction with Vp/Vs and other logs as an aid in formation evaluation for the detection of gas, condensate, and oil. Several case studies in the literature report high P-wave energy absorption at seismic frequencies below gas and condensate pools. This suggests that it is not unreasonable to assume that this method could also be used in seismic exploration as an aid for distinguishing gas and condensate from oil and water formations

A Review on Recent Advances for Electrochemical Reduction of Carbon Dioxide to Methanol Using Metal–Organic Framework (MOF) and Non-MOF Catalysts: Challenges and Future Prospects

Abstract: Transformation of carbon dioxide into various chemicals including methanol is a top priority field of study owing to the association of CO2 with global warming. There is a need for renewable and sustainable energy sources and replacement of fossil fuel with a fuel having comparable energy density. Electrochemical reduction is a unique approach to convert CO2 to methanol by employing alternative energy sources where electrocatalyst plays a crucial role. A lot of effort is made to understand and increase the efficiency of electrocatalysts. Unadulterated metals, metal oxide, composite materials, and metal–organic frameworks (MOFs) are employed for the electrochemical reduction of CO2 to methanol. However, MOFs engrossed the enormous consideration due to simplicity, higher surface area, and unique structural features. In recent years, MOFs and their derivatives find significant applications in the electrocatalysis of oxygen and hydrogen evolution, oxygen, hydrogen, and CO2 reduction. The primary emphasis of t...

An XPS study of iron sodium silicate glass surfaces

Abstract: A series of (SiO2)0.7−x(Na2O)0.3(Fe2O3)x glasses (0.0 ≤ x ≤ 0.18) were prepared and investigated by means of X-ray photoelectron spectroscopy (XPS). The quantitative ratio [Fe2+]/[Fetotal], for each glass has been determined from an analysis of the Fe 3p spectra. For low Fe2O3 content both iron valencies are present, however, it was found that Fe3+ is the dominant species for high Fe2O3. From an analysis of the O 1s spectra, it was possible to discriminate between bridging and non-bridging oxygen atoms. It was found that the ratio of the non-bridging oxygen content to the total oxygen content increases with increasing iron concentration. It has also been shown that the non-bridging oxygen contribution to the O 1s spectra can be simulated by summing the contributions from the SiONa, SiOFe(II) and SiOFe(III) components present in the glass.