scholarly journals Process Intensification in Photocatalytic Decomposition of Formic Acid over a TiO2 Catalyst by Forced Periodic Modulation of Concentration, Temperature, Flowrate and Light Intensity

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2046
Author(s):  
Thomas Ellwood ◽  
Luka A. Živković ◽  
Petr Denissenko ◽  
Rufat Sh. Abiev ◽  
Evgeny V. Rebrov ◽  
...  
Keyword(s):  
Light Intensity ◽  
Formic Acid ◽  
Acid Concentration ◽  
Active Sites ◽  
Molar Fraction ◽  
Photocatalytic Decomposition ◽  
Nonlinear Frequency ◽  
Periodic Modulation ◽  
Reactor Model ◽  
Input Parameters

The effect of forced periodic modulation of several input parameters on the rate of photocatalytic decomposition of formic acid over a TiO2 thin film catalyst has been investigated in a continuously stirred tank reactor. The kinetic model was adopted based on the literature and it includes acid adsorption, desorption steps, the formation of photocatalytic active sites and decomposition of the adsorbed species over the active titania sites. A reactor model was developed that describes mass balances of reactive species. The analysis of the reactor was performed with a computer-aided nonlinear frequency response method. Initially, the effect of amplitude and frequency of four input parameters (flowrate, acid concentration, temperature and light intensity) were studied. All single inputs provided only a minor improvement, which did not exceed 4%. However, a modulation of two input parameters, inlet flowrate and the acid molar fraction, considerably improved the acid conversion from 80 to 96%. This is equivalent to a factor of two increase in residence time at steady-state operation at the same temperature and acid concentration.

scholarly journals OPTIMASI PRODUKSI PULP FORMACELL DARI TANDAN KOSONG KELAPA SAWIT (TKKS) DENGAN METODE PERMUKAAN RESPON

REAKTOR ◽  
2017 ◽  
Vol 16 (4) ◽  
pp. 161 ◽  
Author(s):  
Sri Hidayati ◽  
Ahmad Sapta Zuidar ◽  
Ahmad Fahreza
Keyword(s):  
Formic Acid ◽  
Acid Concentration ◽  
Oil Palm ◽  
Optimum Concentration ◽  
Optimum Result ◽  
Hcl Concentration ◽  
Pulp Production

ABSTRACT Empty oil-palm bunches (EOPB) contains more enough cellulose so that it can be made as an alternative pulp production.  One of the process of pulp production which friendly environment is by using acetate acid and formic acid called by formacell process.  The aims of the research is to got optimation models of formic acid concentration, HCl concentration and cooking duration for the EFB pulp production.  The optimum result of the EOPB pulp production were 75% of cellulose, 8% of hemiselulosa, 10% of  lignin, and 80% of yield with the optimum concentration 20% of formic acid, 0,5% of HCl, and 2 hour of cooking duration.   Keyword : pulp formacell, EFB, RSM.   ABSTRAK Tandan kosong kelapa sawit (TKKS) mengandung kadar selulosa yang cukup tinggi sehingga dapat dijadikan sebagai bahan baku alternatif produksi pulp.  Salah satu proses produksi pulp ramah lingkungan yaitu dengan menggunakan campuran pelarut asam asetat dan asam formiat sebagai bahan pemasak yang disebut proses formacell.  Tujuan dari penelitian ini untuk mendapatkan model optimasi dari konsentrasi asam formiat, konsentrasi HCl dan lama pemasakan untuk produksi pulp TKKS.  Konsentrasi pemasakan optimum terjadi pada konsentrasi asam formiat 20%, konsentrasi HCl 0,5%, dan lama pemasakan selama 2 jam dengan hasil optimum untuk produksi pulp TKKS yaitu 75 % selulosa, 8 % hemiselulosa, 10% lignin, dan 80% rendemen.   Kata kunci: pulp formacell, TKKS, RSM.    

Light-intensity dependence in photocatalytic decomposition of water over K4Nb6O17 catalyst

1994 ◽  
Vol 28 (2-4) ◽  
pp. 417-422 ◽  
Author(s):  
S. Tabata ◽  
H. Ohnishi ◽  
E. Yagasaki ◽  
M. Ippommatsu ◽  
K. Domen
Keyword(s):  
Light Intensity ◽  
Photocatalytic Decomposition ◽  
Intensity Dependence ◽  
Decomposition Of Water

scholarly journals Effectiveness of photodecomposition of rhodamine B and malachite green upon coupled tricomponent TiO2(Anatase-Rutile)/ZnO nanocomposite

2013 ◽  
Vol 6 (2) ◽  
pp. 245-255 ◽  
Author(s):  
Dongfang Zhang
Keyword(s):  
Malachite Green ◽  
Rhodamine B ◽  
Active Sites ◽  
Diffuse Reflectance Spectroscopy ◽  
Organic Dyes ◽  
Synergistic Effects ◽  
Sol Gel ◽  
Photocatalytic Decomposition ◽  
Photoluminescence Intensity ◽  
Tio2 Anatase

Abstract In this study, mixed phase ZnO-TiO2 nanocomposite consisting of hexagonal ZnO and anatase/rutile TiO2 has been synthesized via sol-gel process.The physical and photochemical properties of samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminscience spectra (PL) and and photocurrent action spectra techniques. In the case of minerlization of rhodamine B (RhB) and malachite green (MG) dyes, the coupled ZnO-TiO2 nanocomposite with the suitable band structure and the lowest photoluminescence intensity showed the best photodecolorization activity. Synergistic effects between the two oxides for photocatalytic decomposition of RhB and MG are proposed to elucidate the decolorization mechanism. The lifetime of electrons and holes was prolonged in the ZnO-anatase/rutile multiple-component system, which can enhance the light harvest and the ability of generating photo-induced electron-hole pairs of active sites, and the favorable electron-transfer properties in the coupled ZnO-TiO2 nanocomposite. Therefore, the as-prepared ZnO-TiO2 nanocomposite showed an excellent efficiency towards the removal of aqueous organic dyes and it is of certain significance for environmental photocatalysis.

scholarly journals Modeling of a–Si:H deposition in a dc glow discharge reactor

1992 ◽  
Vol 7 (8) ◽  
pp. 2160-2181 ◽  
Author(s):  
Dariusz Orlicki ◽  
Vladimir Hlavacek ◽  
Hendrik J. Viljoen
Keyword(s):  
Glow Discharge ◽  
Deposition Rate ◽  
Molar Fraction ◽  
Plasma Chemistry ◽  
Ionization Rate ◽  
Flow Speed ◽  
Dissociation Rate ◽  
Dc Glow Discharge ◽  
Reactor Model ◽  
Amorphous Hydrogenated Silicon

PECVD reactors are increasingly used for the manufacturing of electronic components. This paper presents a reactor model for the deposition of amorphous hydrogenated silicon in a dc glow discharge of Ar–SiH4 The parallel-plate configuration is used in this study. Electron and positive ion densities have been calculated in a self-consistent way. A macroscopic description that is based on the Boltzmann equation with forwardscattering is used to calculate the ionization rate. The dissociation rate constant of SiH4 requires knowledge about the electron energy distribution function. Maxwell and Druyvesteyn distributions are compared and the numerical results show that the deposition rate is lower for the Druyvesteyn distribution. The plasma chemistry model includes silane, silyl, silylene, disilane, hydrogen, and atomic hydrogen. The sensitivity of the deposition rate toward the branching ratios SiH3 and SiH2 as well as H2 and H during silyl dissociation is examined. Further parameters that are considered in the sensitivity analysis include anode/cathode temperatures, pressure, applied voltage, gap distance, gap length, molar fraction of SiH4, and flow speed. This work offers insight into the effects of all design and control variables.

scholarly journals Single Isolated Pd2+ Cations Supported on N-Doped Carbon as Active Sites for Hydrogen Production from Formic Acid Decomposition

ACS Catalysis ◽  
2015 ◽  
Vol 6 (2) ◽  
pp. 681-691 ◽  
Author(s):  
Dmitri A. Bulushev ◽  
Monika Zacharska ◽  
Elena V. Shlyakhova ◽  
Andrey L. Chuvilin ◽  
Yina Guo ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Formic Acid ◽  
Active Sites ◽  
Acid Decomposition ◽  
Formic Acid Decomposition

Simultaneous assay of multiple antibiotics in human plasma by LC–MS/MS: importance of optimizing formic acid concentration

Bioanalysis ◽  
2017 ◽  
Vol 9 (5) ◽  
pp. 469-483 ◽  
Author(s):  
Feng Chen ◽  
Zhe-Yi Hu ◽  
S Casey Laizure ◽  
Joanna Q Hudson
Keyword(s):  
Formic Acid ◽  
Human Plasma ◽  
Acid Concentration ◽  
Multiple Antibiotics

Facile Synthesis of Porous Pd3 Pt Half-Shells with Rich “Active Sites” as Efficient Catalysts for Formic Acid Oxidation

Small ◽  
2018 ◽  
Vol 14 (13) ◽  
pp. 1703940 ◽  
Author(s):  
Xiaoxiao Yan ◽  
Xuejiao Hu ◽  
Gengtao Fu ◽  
Lin Xu ◽  
Jong-Min Lee ◽  
...  
Keyword(s):  
Formic Acid ◽  
Active Sites ◽  
Formic Acid Oxidation ◽  
Acid Oxidation ◽  
Facile Synthesis

scholarly journals Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1542
Author(s):  
Mohamad Rasid Shera Farisya ◽  
Ramli Irmawati ◽  
Ishak Nor Shafizah ◽  
Yun Hin Taufiq-Yap ◽  
Ernee Noryana Muhamad ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Surface Area ◽  
Acid Concentration ◽  
Active Sites ◽  
Solid Acid Catalyst ◽  
Sulfuric Acid Concentration ◽  
Catalyst Loading ◽  
Impregnation Method ◽  
Sulfated Titania ◽  
Glycerol Conversion

In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%).

scholarly journals Electro-reduction of carbon dioxide at low over-potential at a metal–organic framework decorated cathode

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xinchen Kang ◽  
Lili Li ◽  
Alena Sheveleva ◽  
Xue Han ◽  
Jiangnan Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Formic Acid ◽  
Active Sites ◽  
Metal Organic Framework ◽  
Computational Modelling ◽  
Structural Defects ◽  
Resonance Spectroscopy ◽  
Faradaic Efficiency ◽  
Metal Organic ◽  
Organic Framework

Abstract Electrochemical reduction of carbon dioxide is a clean and highly attractive strategy for the production of organic products. However, this is hindered severely by the high negative potential required to activate carbon dioxide. Here, we report the preparation of a copper-electrode onto which the porous metal–organic framework [Cu2(L)] [H4L = 4,4′,4″,4′′′-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid] can be deposited by electro-synthesis templated by an ionic liquid. This decorated electrode shows a remarkable onset potential for reduction of carbon dioxide to formic acid at −1.45 V vs. Ag/Ag+, representing a low value for electro-reduction of carbon dioxide in an organic electrolyte. A current density of 65.8 mA·cm−2 at −1.8 V vs. Ag/Ag+ is observed with a Faradaic efficiency to formic acid of 90.5%. Electron paramagnetic resonance spectroscopy confirms that the templated electro-synthesis affords structural defects in the metal–organic framework film comprising uncoupled Cu(II) centres homogenously distributed throughout. These active sites promote catalytic performance as confirmed by computational modelling.

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