104,696 research outputs found
Continuous Flow Photocatalytic Degradation of Phenol Using Palladium@Mesoporous TiO2 Core@Shell Nanoparticles
No full textPalladium@mesoporous titania core@shell nanoparticles with uniform and narrow particle size distribution were synthesised using a four component “water in oil” microemulsion system. The prepared materials were well characterised using N2 adsorption–desorption measurements, temperature program oxidation, X-ray diffraction, ICP-OES, DRS UV-Vis, PL, TGA and transmission electron microscopy techniques. The core@shell nanoparticles showed very good absorption in both the UV and visible regions and a low bandgap, indicating that the prepared materials are visiblelight-active, unlike the pristine TiO2 P25. The activity of the prepared materials was evaluated in the photodegradation of phenol using both UV and visible light, in batch and continuous flow trickle-bed and Taylor flow photoreactors. The prepared 2%Pd@mTiO2 core@shell nanoparticles showed better photocatalytic performance for phenol degradation in visible light in comparison to pristine TiO2 P25 and conventional 0.5%Pd/TiO2 P25 catalysts. The TiO2 P25 and conventional 0.5%Pd/TiO2 P25 catalysts showed gradual catalyst deactivation due to photocorrosion, the deposition of intermediates and Pd metal leaching. In comparison, the 2%Pd@mTiO2 catalyst showed higher catalyst stability and reusability. The 2%Pd@mTiO2 catalysts showed very high and stable phenol degradation (97% conversion) in continuous flow over 52 h. The results showed the feasibility of utilising the developed continuous Taylor flow photoreactor for phenol degradation or as a wastewater treatment plant
Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts
No full textOctahedral molecular sieves (OMS-2) are an interesting form of manganese oxide with a 2 × 2 edge sharing tunnel structure and a cation positioned inside. Cryptomelane is an OMS-2 material with K+ cations within the crystalline tunnel and has been widely used in catalytic oxidation reactions, due to a mixed valency of Mn3+ and Mn4+ cations. Cryptomelane (K-OMS-2) can be modified by structural incorporation of various dopants and tunnel cations which can enhance the catalytic activity of the material. It also offers to be a promising alternative material for the low temperature emission control of combustion vehicles; particularly during cold start and low temperature conditions of diesel vehicles. In this work we used a one-pot sol–gel route to synthesize a range of manganese oxide based supports doped with Ce and CeZrO2, as alternative low temperature diesel oxidation catalysts. We have investigated the combination of manganese, ceria and zirconia in mixed oxide catalyst supports. The synthesized samples were loaded with 1 wt% Pt and their activity in the oxidation reactions of CO and C3H6, were compared with a commercial diesel oxidation catalyst with the same metal loading. The reductions in CO and C3H6 oxidation temperature T50 of 109 K and 81 K respectively was achieved compared to a commercial diesel oxidation catalyst
Intensifying levulinic acid hydrogenation using mechanochemically prepared copper on manganese oxide catalysts
No full textA series of copper nanoparticles supported on manganese oxide octahedral molecular sieves (OMS-2) were prepared using mechanochemical (Ball-Mill) and conventional wet-impregnation (Wet-Imp) methods. All catalysts prepared were thoroughly characterized using ICP-OES elemental analysis, X-ray diffraction (XRD), N2 sorption, H2 temperature programmed reduction (TPR) and transmission electron microscopy (TEM) techniques. The catalyst preparation methods greatly affected the size of the Cu nanoparticles. TEM images showed that 5 wt% Cu/OMS-2 (Ball-Mill) catalyst had a narrow particle size distribution with an average Cu nanoparticle size of 2.1 nm, while the corresponding 5 wt% Cu/OMS-2 catalyst prepared using wet-impregnation method had an average Cu nanoparticle size of 19.2 nm. The structural features of the catalysts were corelated with the catalytic activity using the liquid phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), as an exemplar process. In LA hydrogenation at 190 °C and 20 bar H2 pressure, the ball milled catalysts achieved higher LA conversion, and greater GVL yield, as compared to the corresponding catalysts prepared by wet-impregnation method, reinforcing that Cu nanoparticle size and metal dispersion are important tool to intensify the catalytic activity. For instance, 5 wt% Cu/OMS-2 (Ball-Mill) catalyst achieved almost twice the turnover frequency (TOF), 24.7 h−1 as compared to the 5 wt% Cu/OMS-2 (Wet-Imp) catalyst, TOF 11.8 h−1, under identical reaction conditions. The results of this study demonstrate that ball milling is a superior method for Cu/OMS-2 catalyst preparation than wet impregnation.<br/
Recent advances in catalyst design for carboxylation using CO<sub>2</sub> as the C1 feedstock
No full textCarbon dioxide is ideal for carboxylation reactions as a renewable and sustainable C1 feedstock and has significant recognition owing to its low cost, non-toxicity, and high abundance. To depreciate the environmental concentration of CO2, which causes the greenhouse gas effect, developing new catalytic protocols for organic synthesis in CO2 utilization is of great importance. This review focuses on carboxylation reactions using CO2 as a C1 feedstock to synthesize value-added functionalized carboxylic acids and their corresponding derivatives via catalytically generated allyl metal intermediates, photoredox catalysis, and electrocatalysis with a focus on recent developments and opportunities in catalyst design for carboxylation reactions. In this article, we describe recent developments in the carboxylation of C–H bonds, alkenes, and alkynes using CO2 as the C1 source for various reactions under different conditions, as well as the potential direction for the further development of CO2 utilization in organic synthesis.<br/
Perancangan Instalasi Pompa Distribusi Air Bersih Reservoar Spam Sembayat Menuju Kawasan Industri Manyar
No full textPompa merupakan suatu mesin yang berfungsi untuk memindahkan fluida melalui sisttem perpipaan dengan cara merubah energi mekanis menjadi energi fluida dan tekanan. Terdapat banyak jenis pompa yang terdapat di industri, khususnya pada instalasi penjernihan air bersih PDAM. Maka dibutuhkan pompa yang sesuai dengan kapasitas dan head yang diperlukan untuk mengalirkan fluida cair melewati berbagi macam sistem perpipaan. Distribusi air bersih dari SPAM Sembayat menuju Kawasan Industri Manyar dibutuhkan kapasitas 600 lps, dengan menggunakan 2 pompa yang dioprasikan secara paralel. Tujuan proyek akhir ini diharapkan dapat memilih pompa yang sesuai. Sehingga Kebutuhan air pada kawasan industri Manyar, Gresik dalam kondisi normal adalah 600 lps. Dimana kondisi existing SPAM Sembayat telah menyediakan 3 lokasi pompa. Sehingga pada proyek akhir ini bagaimana merancang instalasi pompa yang sesuai dengan kebutuhan Kawasan Industri Manyar tersebut. Dengan permasalahan yang ada di SPAM Sembayat menuju Kawasan Industri Manyar maka solusi dari permasalahan tersebut adalah sebagai berikut Merencanakan diameter pipa yang digunakan, Perhitungan head effektif instalasi air bersih, Pemilihan pompa dan menentukan titik kerja operasi paralel 2 pompa. Hal ini dapat ditentukan dengan cara melakukan perhitungan meliputi penentuan diameter awal pipa, menentukan material pipa yang dibutuhkan, menghitung kecepatan aliran air didalam pipa, menghitung headloss mayor didalam pipa, menentukan headloss minor didalam pipa, menentukan head total pada setiap pipa, menentukan headloss total pada instalasi pipa, menentukan head effektif instalasi. Maka dari hal tersebut dapat ditarik sebuah kesimpulan Pada Instalasi Perpipaan PDAM yang terjadi di SPAM Reservoar Sembayat menuju Kawasan Industri Manyar pompa yang direkomendasikan adalah jenis pompa Wilo SCP 250-450HA, dikarenakan pada pompa ini memiliki karakteristik Q = 1260 m^3/h, H = 50 m, dan Power = 250 KW. Sehingga pompa ini mampu menyalurkan air PDAM yang telah terpasang pada sistem instalasi perpipaan hingga connection line. Apabila dihubungkan melalui jalur perpipaan menuju Kawasan Industri Manyar dengan menggunakan kombinasi bahan pipa berupa Steel Pipe STD Wall dan HDPE SDR 21 dengan diameter pipa 600 mm maka dapat disimpulkan
Novel Ionic Liquid Synthesis of Bimetallic Fe–Ru Catalysts for the Direct Hydrogenation of CO2 to Short Chain Hydrocarbons
No full textThe selective hydrogenation of CO2 for the production of net-zero fuels and essential chemical building blocks is a promising approach to combat climate change. Key to this endeavor is the development of catalysts with high activity and selectivity for desired hydrocarbon products in the C2–C5 range. The process involves a two-step reaction, starting with the reverse water–gas shift (RWGS) reaction and proceeding to the Fischer–Tropsch reactions under high pressure. Understanding the catalyst features that control the selectivity of these pathways is crucial for product formation, as well as identifying morphological changes in the catalysts during the reaction to optimize their performance. In this study, an innovative method for synthesizing iron–ruthenium bimetallic catalysts is introduced, capitalizing on the synergistic effects of these metals as active phases. This method leverages ionic liquids as solvents, allowing for the precise and uniform distribution of active metal phases. Advanced characterizations and extensive catalytic tests have demonstrated that the use of ionic liquids outperformed traditional colloid-based techniques, resulting in superior selectivity for target hydrocarbons. The success of this inventive approach not only advances the field of CO2 hydrogenation catalysis, but also represents a significant stride towards sustainable e-fuel production
Techno-Economic Assessment and Sensitivity Analysis of Glycerol Valorization to Biofuel Additives via Esterification
No full textGlycerol is a valuablefeedstock, produced in biorefineries asa byproduct of biodiesel production. Esterification of glycerol withacetic acid yields a mixture of mono-, di-, and triacetins. The acetinsare commercially important value-added products with a wide rangeof industrial applications as fuel additives and fine chemicals. Esterificationof glycerol to acetins substantially increases the environmental sustainabilityand economic viability of the biorefinery concept. Among the acetins,diacetin (DA) and triacetin (TA) are considered high-energy-densityfuel additives. Herein, we have studied the economic feasibility ofa facility producing DA and TA by a two-stage process using 100,000tons of glycerol per year using Aspen Plus. The capital costs wereestimated by Aspen Process Economic Analyzer software. The analysisindicates that the capital costs are 71 M/year. The gross profit is 60.5 M with a payback period of 1.7 years. Sensitivityanalysis has indicated that the product price has the most impacton the NPV
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