Enhanced hydrogen-assisted cracking of 1,3,5-triisopropylbenzene over fibrous silica ZSM-5: Influence of co-surfactant during synthesis

In this study, unique fibrous silica ZSM-5 was successfully synthesized by using three type of alcohol possessing different alkyl-chain length as the co-surfactant. The effect of diverse co-surfactant was observed in the changes of physical properties, such as crystallinity, inter-dendrimer distances and pore properties. According to the IR and temperature programmed desorption of ammonia (NH₃-TPD) analyses, all catalysts exhibited different acid strengths which could be triggered by the different amount of additional silica species. All catalysts exhibited high catalytic performance in the hydrocracking of 1,3,5-triisopropylbenzene due to the absence of diffusion limitation. However, FZSM5C3 exhibited the highest catalytic activity which corresponded to its high number of Brønsted acid sites. It was observed that different length of co-surfactant alkyl-chain has resulted in different degree of oil penetration into the microemulsion system which subsequently triggered in various inter-dendrimer distances and amount of incorporated silica species. Hence, the altered physicochemical properties led to the difference in catalytic performance due to the presence of different number of Brønsted acid sites.     

The effects of fuel-injection timing at medium injection pressure on the engine characteristics and emissions of a CNG-DI engine fueled by a small amount of hydrogen in CNG

The experiments to determine the effect of fuel-injection timings on engine characteristics and emissions of a DI engine fueled with NG-hydrogen blends (0%, 3%, 5% and 8%) at various engine speeds were conducted. Three injection timings namely 120°, 180° and 300° CA BTDC with a wide open throttle at relative air-fuel ratio, λ = 1.0 were selected. The ignition advance angle was fixed at 30° CA BTDC, while the injection pressure was fixed at 1.4 MPa for all the cases. The tests were firstly performed at low engine speed of 2000 rpm to determine the engine characteristics and emissions. The results showed that the engine performance (e.g. Brake Torque, Brake Power and BMEP), the cylinder pressure and the heat release have the highest values at the injection timing of 180° CA BTDC, followed by the 300° CA BTDC and the 120° CA BTDC. The NO_x emission was found to be highest at the injection timing of 180° CA BTDC. The THC and CO emissions were found to decrease while the CO₂ emission increased with the advancement in the injection timing. The addition of a small amount of hydrogen to the natural gas was found to increase the engine performance, enhance combustion and reduce emissions for any selected injection timings. Secondly, the tests were carried out at variable engine speeds (i.e. 2000 rpm-4000 rpm) in order to further investigate the engine performance. The injection timings of 180° and 300° CA BTDC with CNG-H₂ blends were only selected for comparisons. The injection timing of the 300° CA BTDC was discovered to yield better engine performance as compared to the 180° CA BTDC injection timing after a cutoff engine speed of approximately 2500 rpm.     

Real-Time FPGA Implementation of FIR Filter Using OpenCL Design

Journal of Signal Processing Systems - This paper proposes the implementation of a real-time finite impulse response (FIR) filter with a field-programmable gate array (FPGA) and Open Computing...     

Shorting strap tunable single feed dual-band PIFA

RF switches are integrated to the shorting straps of a single feed dual-band planar inverted-F antenna (PIFA) to make a tunable PIFA. The L-band switch yields 0.45-dB insertion loss (IL) and 10-dB isolation bandwidth (BW) of 40% at 1.5 GHz. The tunable PIFA yields 39% impedance BW at 900-MHz band and 7.8% BW at 2000-MHz band. The measured radiation patterns are nearly omni-directional and yield a gain of -7.8 dBi at 652 MHz and 4.3 dBi at 2104 MHz.     

Production of hydrogen via steam reforming of acetic acid over Ni and Co supported on La2O3 catalyst

Nickel (Ni)-cobalt (Co) supported on lanthanum (III) oxide (La₂O₃) catalyst was prepared via impregnation technique to study the steam reformation of acetic acid for hydrogen generation by using one-step fixed bed reactor. Moreover, in order to specify the physical and the chemical attributes of the catalyst, X-ray diffraction (XRD), nitrogen physisorption, temperature-programmed reduction (TPR), temperature-programmed desorption of ammonia and carbon dioxide (TPD-NH₃ and CO₂), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) methods were employed. The nitrogen physisorption analysis showed that the presence of Co on Ni/La₂O₃ improved the textural properties of the catalyst by increasing the surface area, the pore diameter and the pore volume of the catalyst. This improved the dispersion of metal particle and caused a reduction in the size of metal particle, and consequently, increased the catalytic activity, as well as the resistance to coke formation. On top of that, the condensation and the dehydration reactions during acetic acid steam reforming created carbon deposition on acidic site of the catalyst, which resulted in the deactivation of catalyst and the formation of coke. Besides, in this study, Ni/La₂O₃ contributed to a high acetic acid conversion (100%) at 700 °C, but it produced more coking compared to Ni–Co/La₂O₃ and Co/La₂O₃ catalysts.