50 research outputs found

    Carbon Dioxide To Methanol: Stoichiometric Catalytic Hydrogenation Under High Pressure Conditions

    Get PDF
    El CO2 en la atm贸sfera aumenta a ra铆z del empleo de combustibles f贸siles. La hidrogenaci贸n de CO2 ofrece una ruta 煤nica para transformar esta mol茅cula en productos qu铆micos o combustibles como el metanol. El uso de alta presi贸n en el ratio CO2:H2 = 1:>3 permite incrementar la cin茅tica de la reacci贸n, alcanzando as铆 la conversi贸n termodin谩mica como ya se ha reportado. No obstante, el mayor inconveniente del mencionado proceso es el tratamiento del hidr贸geno sin reaccionar. Por ello, se evaluaron las ventajas de realizar la reacci贸n a alta presi贸n en condiciones estequiom茅tricas (CO2:H2=1:3) examinando diferentes par谩metros. Una vez optimizados, se alcanz贸 el l铆mite termodin谩mico y se obtuvo un valor de conversi贸n de CO2 cercano al 90% con una selectividad para metanol > 95% a 280 掳C y 442 bar empleando Cu/ZnO/AlO3 como catalizador. Al minimizar las limitaciones de transferencia de masa, el rendimiento fue de 15.6 gMeOH gcat-1 h-1, aproximadamente un orden de magnitud mayor comparado con los de bibliograf铆a. Adicionalmente, los mecanismos de la reacci贸n en condiciones de alta presi贸n se estudiaron mediante an谩lisis espacial de la fase gas por CG y espectroscop铆a Raman. El estudio mostr贸 que el CO2 se convierte directamente a metanol a baja temperatura, mientras que a alta temperatura la reacci贸n water-gas shift es predominante generando CO, que produce metanol posteriormente. estructura core-shell. Este material mostr贸 un recubrimiento uniforme del ZnO en los cores de Cu, y el espesor del shell se optimiz贸. Dichos nanomateriales mostraron alta actividad catal铆tica, 煤til para comprender la interacci贸n entre Cu y Zn y en concreto, las exclusivas fases de Zn formadas durante la reacci贸n a alta presi贸n mediante operando DRX a alta presi贸n.Carbon dioxide concentration in the atmosphere is continuously increasing as a consequence of the combustion of fossil fuels. CO2 hydrogenation offers a unique path to transform the chemically stable CO2 to useful chemicals or fuel such as methanol. High-pressure advantages under over-stoichiometric CO2:H2 ratio (1:>3) has been reported previously by drastically increasing the reaction kinetics and even reaching the thermodynamic conversion. However, the major drawback of such processes is the treatment of unreacted hydrogen. Reflecting this background, the advantages of the high pressure approach in stoichiometric CO2:H2 (1:3) ratio were critically evaluated by examining different reaction and process parameters. When optimized, we could reach the thermodynamic limit and obtained about 90% CO2 conversion with >95% methanol selectivity at 280 掳C and 442 bar using Cu/ZnO/Al2O3 catalyst. When the mass transfer limitation was minimized, an outstanding weight time yield was achieved with 15.6 gMeOH gcat-1 h-1, which is about one order of magnitude higher than the state-of-the-art values. Furthermore, the reaction mechanisms under high-pressure reaction conditions were studied by spatially-resolved gas phase analysis through the axial direction of the catalytic reactor by GC and Raman spectroscopy

    A Review on Smart Home Automation using Virtue of IoT

    Get PDF
    Smart home automation system in daily routine plays a starring role which helps in reducing work. Smart home automation is flattering trendy due to its various advantages. With development of Automation technology, life is getting effortless and uncomplicated in all aspects and it is intended to save the electric power and human energy besides automated systems are being favored more than manual system. With the speedy enhancement in the number of users of internet over the past decade has made Internet an essential part of life. Nowadays IoT is the most recent and promising internet technology. This paper describes the literature survey of existing system. We will perceive a review of the technology used to design this system. Comparisons of different system technology are studied in this paper.

    Mobilization of Stem Cells Using G-CSF for Acute Ischemic Stroke: A Randomized Controlled, Pilot Study

    Get PDF
    Background. There is emerging evidence to support the use of granulocyte colony-stimulating factor (G-CSF) therapy in patients with acute ischemic stroke. Aims. To explore feasibility, safety, and preliminary efficacy of G-CSF therapy in patients with acute ischemic stroke. Patients and Method. In randomized study, 10 patients with acute ischemic stroke were recruited in 1鈥:鈥1 ratio to receive 10鈥壩糶/kg G-CSF treatment subcutaneously daily for five days with conventional care or conventional treatment alone. Efficacy outcome measures were assessed at baseline, one month, and after six months of treatment included Barthel Index (BI), National Institute of Health Stroke Scale, and modified Rankin Scale. Results. One patient in G-CSF therapy arm died due to raised intracranial pressure. No severe adverse effects were seen in rest of patients receiving G-CSF therapy arm or control arm. No statistically significant difference between intervention and control was observed in any of the scores though a trend of higher improvement of BI score is seen in the intervention group. Conclusion. Although this study did not have power to examine efficacy, it provides preliminary evidence of potential safety, feasibility, and tolerability of G-CSF therapy. Further studies need to be done on a large sample to confirm the results

    Carbon Dioxide To Methanol: Stoichiometric Catalytic Hydrogenation Under High Pressure Conditions

    Get PDF
    El CO2 en la atm贸sfera aumenta a ra铆z del empleo de combustibles f贸siles. La hidrogenaci贸n de CO2 ofrece una ruta 煤nica para transformar esta mol茅cula en productos qu铆micos o combustibles como el metanol. El uso de alta presi贸n en el ratio CO2:H2 = 1:>3 permite incrementar la cin茅tica de la reacci贸n, alcanzando as铆 la conversi贸n termodin谩mica como ya se ha reportado. No obstante, el mayor inconveniente del mencionado proceso es el tratamiento del hidr贸geno sin reaccionar. Por ello, se evaluaron las ventajas de realizar la reacci贸n a alta presi贸n en condiciones estequiom茅tricas (CO2:H2=1:3) examinando diferentes par谩metros. Una vez optimizados, se alcanz贸 el l铆mite termodin谩mico y se obtuvo un valor de conversi贸n de CO2 cercano al 90% con una selectividad para metanol > 95% a 280 掳C y 442 bar empleando Cu/ZnO/AlO3 como catalizador. Al minimizar las limitaciones de transferencia de masa, el rendimiento fue de 15.6 gMeOH gcat-1 h-1, aproximadamente un orden de magnitud mayor comparado con los de bibliograf铆a. Adicionalmente, los mecanismos de la reacci贸n en condiciones de alta presi贸n se estudiaron mediante an谩lisis espacial de la fase gas por CG y espectroscop铆a Raman. El estudio mostr贸 que el CO2 se convierte directamente a metanol a baja temperatura, mientras que a alta temperatura la reacci贸n water-gas shift es predominante generando CO, que produce metanol posteriormente. estructura core-shell. Este material mostr贸 un recubrimiento uniforme del ZnO en los cores de Cu, y el espesor del shell se optimiz贸. Dichos nanomateriales mostraron alta actividad catal铆tica, 煤til para comprender la interacci贸n entre Cu y Zn y en concreto, las exclusivas fases de Zn formadas durante la reacci贸n a alta presi贸n mediante operando DRX a alta presi贸n.Carbon dioxide concentration in the atmosphere is continuously increasing as a consequence of the combustion of fossil fuels. CO2 hydrogenation offers a unique path to transform the chemically stable CO2 to useful chemicals or fuel such as methanol. High-pressure advantages under over-stoichiometric CO2:H2 ratio (1:>3) has been reported previously by drastically increasing the reaction kinetics and even reaching the thermodynamic conversion. However, the major drawback of such processes is the treatment of unreacted hydrogen. Reflecting this background, the advantages of the high pressure approach in stoichiometric CO2:H2 (1:3) ratio were critically evaluated by examining different reaction and process parameters. When optimized, we could reach the thermodynamic limit and obtained about 90% CO2 conversion with >95% methanol selectivity at 280 掳C and 442 bar using Cu/ZnO/Al2O3 catalyst. When the mass transfer limitation was minimized, an outstanding weight time yield was achieved with 15.6 gMeOH gcat-1 h-1, which is about one order of magnitude higher than the state-of-the-art values. Furthermore, the reaction mechanisms under high-pressure reaction conditions were studied by spatially-resolved gas phase analysis through the axial direction of the catalytic reactor by GC and Raman spectroscopy

    Optimal Transmit Spectra for HDSL2

    No full text
    ReportWe present a general framework for designing optimal transmit spectra for the HDSL2 service. Using the channel and interference transfer functions and SNR estimates, we set up and solve an optimization problem to maximize the capacity. Sizable gains in performance margins (or bit rates) result. Furthermore, by design, the spectra are spectrally compatible with other services. While the framework is quite general - it does not depend on the exact choice of modulation scheme, for example - it is also extremely simple and of low computationaly complexity. Our results can be used either for dynamically adapting the signaling spectra to account for changing noise or intereference conditions or for the design of new fixed transmit spectral masks using worst-case analysis
    corecore