The gram-scale synthesis, stabilization, and characterization of well-defined ultrasmall subnanometric catalytic clusters on solids is a challenge. The chemical synthesis and X-ray snapshots of Pt02 clusters, homogenously distributed and densely packaged within the channels of a metal-organic framework, is presented. This hybrid material catalyzes efficiently, and even more importantly from an economic and environmental viewpoint, at low temperature (25 to 140 °C), energetically costly industrial reactions in the gas phase such as HCN production, CO2 methanation, and alkene hydrogenations. These results open the way for the design of precisely defined catalytically active ultrasmall metal clusters in solids for technically easier, cheaper, and dramatically less-dangerous industrial reactions.

Synthesis of Densely Packaged, Ultrasmall Pt02 Clusters within a Thioether-Functionalized MOF: Catalytic Activity in Industrial Reactions at Low Temperature

Bioleaching of metals from wastes and low-grade sources by HCN-forming microorganisms

The present invention relates to a method for oligomerizing hydridosilanes, wherein a composition comprising substantially at least one non-cyclic hydridosilane having a maximum of 20 silicon atoms as the hydridosilane is thermally converted at temperatures below 235°C in the absence of a catalyst, the oligomers that can be produced according to the method, and the use thereof.

Method for oligomerizing hydridosilanes, the oligomers that can be produced by means of the method, and the use thereof

The invention relates to a method for producing hydridosilanes from halosilanes by a) reacting i) at least one halosilane of the generic formula SinX2n+2 (with n ≥ 3 and X = F, Cl, Br and/or I) with ii) at least one catalyst of the generic formula NRR'aR"bYc with a = 0 or 1, b = 0 or 1, and c = 0 or 1, and formula (I), wherein aa) R, R' and/or R'' are -C1-C12 alkyl, -C1-C12 aryl, -C1-C12 aralkyl, -C1-C12 aminoalkyl, -C1-C12 aminoaryl, -C1-C12 aminoaralkyl, and/or two or three groups R, R' and R'' (if c = 0) together form a cyclic or bicyclic, heteroaliphatic or heteroaromatic system including N, with the proviso that at least one group R, R' or R'' is unequal -CH3 and/or wherein bb) R and R' and/or R''' (if c = 1) are -C1-C12 alkylene, -C1-C12 arylene, -C1-C12 aralkylene, -C1-C12 heteroalkylene, -C1-C12 heteroarylene, -C1-C12 heteroaralkylene and/or –N=, or cc) (if a = b = c = 0) R = ≡C-R''' (with R''' = -C1-C10 alkyl, -C1-C10 aryI and/or -C1-C10 aralkyl), while forming a mixture comprising at least one halosilane of the generic formula SimX2m+2 (with m > n and X = F, Cl, Br and/or I) and SiX4 (with X = F, Cl, Br and/or I), and b) hydrogenating the at least one halosilane of the generic formula SimH2m+2 while forming a hydridosilane of the generic formula SimH2m+2. The invention also relates to the hydridosilanes producible according to said method and to their use.

Method for producing hydridosilanes

Over the past few decades, crude oil has become the main natural source for meeting the World’s rapidly growing energy needs and for the formation of primary petrochemical building blocks, such as ethylene, propylene, butylenes, and butadiene. However, this growing oil demand is linked with its limited reserves and stricter environmental regulations compel chemical companies to use and search for alternative carbon sources; of these alternatives, natural gas is considered to be a clean and sustainable candidate. It mainly consists of methane, with up to 20 % of C2 C5 hydrocarbons. Indeed, its known reserves exceed those of crude oil. In addition, methane can be produced from biodegradable materials. At present, a major percentage of methane is simply combusted to generate electrical power and heating. The production of hydrocyanic acid through the oxidative and non-oxidative coupling of methane with ammonia is an important commercial process. The steam reforming of methane (SRM) is also industrially used to produce a mixture of CO and H2 (syngas). [3] However, to achieve a H2/CO ratio of 2, as required for MeOH and Fischer– Tropsch (FT) syntheses, the SRM must be combined with a water-gas-shift reaction, thereby resulting in the production of CO2. Even larger amounts of CO2 are produced if syngas is used in very-large-scale ammonia synthesis. Therefore, there is a lot of economic and environmental interest in developing processes that enable the highly selective conversion of methane into higher-valued chemical products without the co-production of CO2. Since the early 1980s, the development of catalysts and/or processes for the direct conversion (i.e. , non-syngas routes) of methane into useful chemical products has been one of the most challenging subjects in catalysis. The oxidative coupling of methane (OCM) to ethane/ethylene and the oxidation of methane into MeOH and/or formaldehyde have been intensively investigated for this purpose. The strong C H bond and the absence of functional groups make CH4 a very unreactive molecule. Moreover, the above-mentioned reaction products are more reactive than methane; as a consequence, they tend to be overoxidized into COx (CO and CO2). Therefore, the main challenge is to develop catalysts that are able to activate methane without combusting the desired products. Despite extensive studies on this subject, all of the catalytic materials that have been tested for the direct oxidative conversion of methane suffer from high COx selectivity at industrially relevant methane conversions. For example, a highest overall yield of MeOH and formaldehyde of only 16 % at 40 % COx selectivity was reported in Ref. [8] ; indeed, Zavyalova et al. analyzed about 1000 scientific papers and patents that dealt with the OCM reaction and found that only a few catalytic materials converted CH4 with COx selectivities below 30 % at conversions above 20 %. Another drawback of this reaction is the need to separate the side-products CO and CO2 from the desired products C2H4 and C2H6 and from unreacted CH4 ; some C2H4 is also removed if scrubbing CO2 and expensive cryogenic techniques are required to separate CO from CH4. Thus, lowering the COx selectivity at industrially relevant CH4 conversions and the development of effective separation technologies are two key aspects for developing economically feasible and environmentally benign processes for CH4 conversion into higher-valued hydrocarbons. Herein, we introduce and experimentally verify a concept for improving the OCM reaction in terms of hydrocarbon selectivity and easy products separation, which may provide a breakthrough for this reaction. The methodology is based on combining the OCM reaction with the selective hydrogenation of COx into light hydrocarbons. To this end, we performed the OCM reaction at high temperatures in a first reactor and a second reactor, which operated at lower temperatures, was used for the hydrogenation of COx into hydrocarbons without the need for expensive pre-separation of the product mixture from the first reactor. In this concept, the hydrogenation catalyst should not catalyze the non-selective formation of CH4 through hydrogenolysis of C2 hydrocarbons that are formed during the OCM reaction and must be active in the presence of excess water. Commercially, the direct FT route with CO is applied over Feand Co-based catalysts. CO2 that is formed as a sideproduct must be recovered, owing to legislative demands. It can also be hydrogenated into hydrocarbons over typical FT catalysts and those that contain noble metals. 12] To the best of our knowledge, there have been no studies on the hydrogenation of CO2 in the presence of C2H4 and excess water at ambient pressure, as required for our above-described concept. Therefore, our primary purpose was to develop a suitable hydrogenation catalyst. To this end, we prepared several supported Co-, Fe-, and Ru-containing catalytic materials and tested them for the hydrogenation of CO2 at 498 K by using a feed that contained CH4, C2H4, CO2, water, and H2; the Supporting Information, Tables S1 and S2, list the catalysts that were applied and their performance. To discriminate between these catalysts, we used the conversion of CO2 and the selectivity of [a] Dr. E. V. Kondratenko, Dr. U. Rodemerck Leibniz-Institut f r Katalyse e.V. an der Universit t Rostock Albert-Einstein-Str. 29 A, 18059 Rostock (Germany) Fax: (+ 49) 381-1281-51290 E-mail : evgenii.kondratenko@catalysis.de Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cctc.201200779.

A Dual‐Reactor Concept for the High‐Yielding Conversion of Methane into Higher Hydrocarbons

The invention relates to a method for producing higher hydridosilane wherein at least one lower hydridosilane and at least one heterogeneous catalyst are brought to reaction, wherein the at least one catalyst comprises Cu, Ni, Cr and/or Co applied to a carrier and/or oxide of Cu, Ni, Cr and/or Co applied to a carrier, the hydridosilane that can be produced according to said method and use thereof.

Process for preparing higher hydridosilanes

The sections in this article are


Introduction
The Andrussow Process
History
Fundamentals
Production of Liquid Hydrocyanic Acid
Pressure Variant
Oxygen Variant
Ammonia Recycling


Reactor and Catalyst


The BMA Process
Overview
Development of the Catalyst
Development of the BMA Tubes
Reactor Design


Mechanism and Kinetics of HCN formation in the BMA and Andrussow Processes
Kinetics and Mechanism of the BMA Process
Thermodynamic Context
HCN and N2 Formation
Coke Formation
On the Role of Gas-Phase Reactions
Catalytically Active Centers


Kinetics and Mechanism of the Andrussow Process
Thermodynamic Relationships
HCN Formation
HCN Hydrolysis
Catalytically Active Centers




Final Remarks


Keywords:

shawinigan process;
Andrussow process;
BMA process;
reactor design and development;
thermodynamics;
high temperatures catalysis

Hydrocyanic Acid (HCN) Production

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Process for preparing higher hydridosilanes

Hydrocyanic Acid (HCN) Production