scholarly journals Bio-DEE Synthesis and Dehydrogenation Coupling of Bio-Ethanol to Bio-Butanol over Multicomponent Mixed Metal Oxide Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 660
Author(s):  
Izabela S. Pieta ◽  
Alicja Michalik ◽  
Elka Kraleva ◽  
Dusan Mrdenovic ◽  
Alicja Sek ◽  
...  
Keyword(s):  
Active Sites ◽  
Internal Combustion Engines ◽  
Mixed Oxides ◽  
Catalyst Activity ◽  
Product Distribution ◽  
Coke Deposition ◽  
Precipitation Method ◽  
Mixed Metal Oxide ◽  
Low Carbon ◽  
Municipal Solid Wastes

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods from municipal solid wastes (MSWs) are sought for application as energy carriers or direct drop-in fuels/chemicals in the near-future low-carbon power generation systems and internal combustion engines. Among the studied energy vectors, C1-C2 alcohols and ethers are mainly addressed. This study presents a potential bio-derived ethanol oxidative coupling in the gas phase in multicomponent systems derived from hydrotalcite-containing precursors. The reaction of alcohol coupling to ethers has great importance due to their uses in different fields. The samples have been synthesized by the co-precipitation method via layered double hydroxide (LDH) material synthesis, with a controlled pH, where the M(II)/M(III) ≈ 0.35. The chemical composition and topology of the sample surface play essential roles in catalyst activity and product distribution. The multiple redox couples Ni2+/Ni3+, Cr2+/Cr3+, Mn2+/Mn3+, and the oxygen-vacant sites were considered as the main active sites. The introduction of Cr (Cr3+/Cr4+) and Mn (Mn3+/Mn4+) into the crystal lattice could enhance the number of oxygen vacancies and affect the acid/base properties of derived mixed oxides, which are considered as crucial parameters for process selectivity towards bio-DEE and bio-butanol, preventing long CH chain formation and coke deposition at the same time.

scholarly journals Cyclodehydration of 1,4-butanediol over Zr-Al Catalysts: Effect of Reaction Medium

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2092 ◽  
Author(s):  
Kuo-Tseng Li ◽  
Kuan-Wen Chen
Keyword(s):  
Surface Area ◽  
Rate Constant ◽  
Active Sites ◽  
Mixed Oxides ◽  
Reaction Medium ◽  
Adsorbed Water ◽  
Precipitation Method ◽  
Catalyst Composition ◽  
Catalyst Acidity ◽  
Co Precipitation

The conversion of 1,4-butanediol (BDO) to tetrahydrofuran (THF) in aqueous phase is desirable because BDO production technology is shifting to bio-based aqueous fermentation routes. In this study, liquid-phase cyclodehydration of BDO to THF was studied in two reaction media (pure BDO and aqueous BDO feeds) at 200–240 °C using ZrO2-Al2O3 (ZA) mixed oxides, which were made with a co-precipitation method and were characterized with XRD, BET, SEM/EDX, pyridine and n-butylamine adsorptions. The maximum acidity and the largest surface area occurred at Zr/Al atomic ratios of 1/1 (ZA11) and 1/3 (ZA13), respectively. The reaction exhibited pseudo-first-order; aqueous BDO feed had much greater rate constant than pure BDO feed, ascribed to the acidic properties of adsorbed water molecules (coordinated to surface metal cations) for the former case. For pure BDO feed, linear relation was observed between rate constant and catalyst acidity, and ZA11 reached a THF yield of 90.1% at 240 °C. With aqueous BDO feed, rate constant increased linearly with increasing surface area and ZA13 reached a THF yield of 97.1% at 220 °C. The change of optimum catalyst composition with reaction medium suggests that active sites for catalyzing BDO cyclodehydration changed with the reaction environment.

scholarly journals Combined Reforming of Clean Biogas over Nanosized Ni–Rh Bimetallic Clusters

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1345
Author(s):  
Nicola Schiaroli ◽  
Carlo Lucarelli ◽  
Maria Carmela Iapalucci ◽  
Giuseppe Fornasari ◽  
Antonio Crimaldi ◽  
...  
Keyword(s):  
Active Sites ◽  
Carbon Deposition ◽  
Bimetallic Nanoparticles ◽  
Catalyst Activity ◽  
Dry Reforming ◽  
Bimetallic Clusters ◽  
Low Carbon ◽  
Reaction Conditions ◽  
Active Particles ◽  
Highly Dispersed

The combined steam/dry reforming of clean biogas (CH4/CO2 = 50/50 v/v) represents an innovative way to produce synthesis gas (CO + H2) using renewable feeds, avoiding to deplete the fossil resources and increase CO2 pollution. The reaction was carried out to optimize the reaction conditions for the production of a syngas with a H2/CO ratio suitable for the production of methanol or fuels without any further upgrading. Ni-Rh/Mg/Al/O catalysts obtained from hydrotalcite-type precursors showed high performances in terms of clean biogas conversion due to the formation of very active and resistant Ni-Rh bimetallic nanoparticles. Through the utilization of a {Ni10Rh(CO)19}{(CH3CH2)4N}3 cluster as a precursor of the active particles, it was possible to promote the Ni-Rh interaction and thus obtain low metal loading catalysts composed by highly dispersed bimetallic nanoparticles supported on the MgO, MgAl2O4 matrix. The optimization of the catalytic formulation improved the size and the distribution of the active sites, leading to a better catalyst activity and stability, with low carbon deposition with time-on-stream.

scholarly journals Biodiesel: Modified Mixed Oxides as Catalyst for Transesterification of Rapeseed Oil

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1397
Author(s):  
Vávra Aleš ◽  
Tišler Zdeněk ◽  
Kocík Jaroslav ◽  
Smutek Jakub
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Fossil Fuels ◽  
Mixed Oxides ◽  
Catalyst Activity ◽  
Textural Properties ◽  
Carbon Fibres ◽  
Key Factor ◽  
Double Hydroxides

Biodiesel, as one of the alternative biofuels replacing the common fossil fuels, is prepared by transesterification of oils and fats. Commonly, the reaction is catalysed by either acidic or basic catalysts. The availability of the active sites to large triglyceride molecules is the key factor of the heterogeneous catalysts. The use of carbon fibres during the synthesis of Mg/Fe layered double hydroxides results in the formation of macropores during the calcination. The amount of carbon fibres showed an important effect on the textural properties of the resulting mixed oxides. The texture was determined by N2-adsorption and Hg-porosity. The catalyst activity in the studied reaction was examined by determination of ester amount by gas chromatography and the activity was compared with unmodified mixed oxides. The highest ester yield (40 wt.%) was achieved by adding 1 wt.% of carbon fibres to the catalyst with the largest size of macropores.

scholarly journals A study of thermally activated Mg-Fe layered double hydroxides as potential environmental catalysts

2010 ◽  
Vol 75 (9) ◽  
pp. 1251-1257 ◽  
Author(s):  
Milica Hadnadjev-Kostic ◽  
Tatjana Vulic ◽  
Radmila Marinkovic-Neducin
Keyword(s):  
Layered Double Hydroxides ◽  
Active Sites ◽  
Single Phase ◽  
Mixed Oxides ◽  
Precipitation Method ◽  
Test Reaction ◽  
Thermally Activated ◽  
Fe Content ◽  
Multiphase Systems ◽  
Double Hydroxides

Layered double hydroxides (LDHs) and mixed oxides derived after thermal decomposition of LDH with different Mg-Fe content were investigated. These materials were chosen because of the possibility to tailor their various properties, such as ion-exchange capability, redox and acid-base properties and surface area. Layered double hydroxides, [Mg1-x Fex (OH)2](CO3)x/2 ? m H2O, (where x presents the content of trivalent ions, x = M(III)/[M(II) + M(III)]) were synthesized, using low supersaturation precipitation method. The influence of different Mg/Fe ratio on the structure and surface properties of LDH and derived mixed oxides was investigated in correlation to catalytic properties in chosen test reaction (Fischer-Tropsch synthesis). It was determined that the presence of active sites in the mixed oxides is influenced by structural properties of the initial LDH and by the presence of additional Fe phases. Furthermore, the synthesis outside the optimal range for the synthesis of single phase LDHs leads to the formation of metastable, multiphase systems with specific characteristics and active sites.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

Assessment of Hydrogen Production from Municipal Solid Wastes as Competitive Route to Produce Low-Carbon H2

2022 ◽  
Author(s):  
Gabriele Centi ◽  
Alessia Borgogna ◽  
Gaetano Iaquaniello ◽  
Siglinda Perathoner ◽  
Annarita Salladini
Keyword(s):  
Hydrogen Production ◽  
Solid Wastes ◽  
Low Carbon ◽  
Municipal Solid Wastes

Rethinking Energy at the Crossroads

2018 ◽  
Author(s):  
Kathleen Araújo
Keyword(s):  
Renewable Energy ◽  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Energy Use ◽  
Clean Energy ◽  
Energy Estimates ◽  
Low Carbon ◽  
Fuel Prices ◽  
New Energy ◽  
Carbon Dioxide Co2

The discovery of oil in Pennsylvania in 1859 was a relatively inconspicuous precursor to what would become an epic shift into the modern age of energy. At the time, the search for “rock oil” was driven by a perception that lighting fuel was running out. Advances in petrochemical refining and internal combustion engines had yet to occur, and oil was more expensive than coal. In less than 100 years, oil gained worldwide prominence as an energy source and traded commodity. Along similar lines, electricity in the early 1900s powered less than 10% of the homes in the United States. Yet, in under a half a century, billions of homes around the world were equipped to utilize the refined form of energy. Estimates indicate that roughly 85% of the world’s population had access to electricity in 2014 (World Bank, n.d.b). For both petroleum and electricity, significant changes in energy use and associated technologies were closely linked to evolutions in infrastructure, institutions, investment, and practices. Today, countless decision-makers are focusing on transforming energy systems from fossil fuels to low carbon energy which is widely deemed to be a cleaner, more sustainable form of energy. As of 2016, 176 countries have renewable energy targets in place, compared to 43 in 2005 (Renewable Energy Policy Network for the 21st Century [REN21], 2017). Many jurisdictions are also setting increasingly ambitious targets for 100% renewable energy or electricity (Bloomberg New Energy Finance [BNEF], 2016). In 2015, the G7 and G20 committed to accelerate the provision of access to renewables and efficiency (REN21, 2016). In conjunction with all of the above priorities, clean energy investment surged in 2015 to a new record of $329 billion, despite low, fossil fuel prices. A significant “decoupling” of economic and carbon dioxide (CO2) growth was also evident, due in part to China’s increased use of renewable energy and efforts by member countries of the Organization for Economic Cooperation and Development (OECD) to foster greater use of renewables and efficiency (REN21, 2016).

2. Why do we need renewables?

2020 ◽  
pp. 16-29
Author(s):  
Nick Jelley
Keyword(s):  
Climate Change ◽  
Carbon Dioxide Emissions ◽  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Wind Farms ◽  
Clean Energy ◽  
Low Carbon ◽  
Net Zero ◽  
Dangerous Climate Change ◽  
Low Carbon Energy

‘Why do we need renewables?’ describes the dangers of fossil fuels and explains the importance of renewable energy as an alternative. It shows that the use of fossil fuels causes global warming and climate change, leading to widespread concern, and also to a growing realization of the harm caused by the air pollution from coal burning and from internal combustion engines in cars and lorries. These threats are causing a switch away from fossil fuels to renewables that is gaining impetus from the growing awareness of the increased intensity and frequency of extreme weather seen in recent years. This transition is also being aided by the falling price of clean energy from renewables, in particular, solar and wind farms, which will become the dominant sources. The area of land or sea required for these farms is readily available, as are the back-ups required to handle their variability. Alternative supplies of low-carbon energy are examined. In the Paris Agreement in 2015, it was recognized that carbon dioxide emissions must reach net-zero by 2050 to avoid dangerous climate change.

scholarly journals Effect of Copper Cobalt Oxide Composition on Oxygen Evolution Electrocatalysts for Anion Exchange Membrane Water Electrolysis

2020 ◽  
Vol 8 ◽  
Author(s):  
Chae-Yeon Kwon ◽  
Jae-Yeop Jeong ◽  
Juchan Yang ◽  
Yoo Sei Park ◽  
Jaehoon Jeong ◽  
...  
Keyword(s):  
Cobalt Oxide ◽  
Anion Exchange ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Anion Exchange Membrane ◽  
Electrochemical Kinetics ◽  
Precipitation Method ◽  
Energetic Efficiency ◽  
Co Precipitation ◽  
Exchange Membrane

Copper cobalt oxide nanoparticles (CCO NPs) were synthesized as an oxygen evolution electrocatalyst via a simple co-precipitation method, with the composition being controlled by altering the precursor ratio to 1:1, 1:2, and 1:3 (Cu:Co) to investigate the effects of composition changes. The effect of the ratio of Cu2+/Co3+ and the degree of oxidation during the co-precipitation and annealing steps on the crystal structure, morphology, and electrocatalytic properties of the produced CCO NPs were studied. The CCO1:2 electrode exhibited an outstanding performance and high stability owing to the suitable electrochemical kinetics, which was provided by the presence of sufficient Co3+ as active sites for oxygen evolution and the uniform sizes of the NPs in the half cell. Furthermore, single cell tests were performed to confirm the possibility of using the synthesized electrocatalyst in a practical water splitting system. The CCO1:2 electrocatalyst was used as an anode to develop an anion exchange membrane water electrolyzer (AEMWE) cell. The full cell showed stable hydrogen production for 100 h with an energetic efficiency of >71%. In addition, it was possible to mass produce the uniform, highly active electrocatalyst for such applications through the co-precipitation method.

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