Oxidative dehydrogenation catalysts comprising MoVNbTeO having improved consistency of composition and a 25% conversion of ethylene at less than 420 C. and a selectivity to ethylene above 95% are prepared by treating the catalyst precursor with H.sub.2O.sub.2 in an amount equivalent to 0.30-2.8 mL H.sub.2O.sub.2 of a 30% solution per gram of catalyst precursor prior to calcining.

Incorporating into a fixed bed reactor for an exothermal reaction having a catalyst supported on a support having a thermal conductivity typically less than 30 W/mk within the reaction temperature control limits heat dissipative particles having a thermal conductivity of at least 50 W/mk less than 30 W/mk within the reaction temperature control limits helps control the temperature of the reactor bed.

The preparation of an oxidative dehydrogenation catalyst comprising Mo, V, Nb and Te using a hydrothermal step. In some embodiments, the activity and reproducibility of the catalyst is improved by conducting the hydrothermal step while permitting gaseous products to leave the reactor. In some instances a condenser may be upstream of the outlet of the reactor.

Oxidative dehydrogenation catalysts for converting lower paraffins to alkenes such as ethane to ethylene when prepared as an agglomeration, for example extruded with supports chosen from slurries of TiO.sub.2, ZrO.sub.2 Al.sub.2O.sub.3, AlO(OH) and mixtures thereof have a lower temperature at which 25% conversion is obtained.

In some embodiments provided herein are processes for controlling carbon dioxide output levels coming from an oxidative dehydrogenation (ODH) process. Carbon dioxide output from an ODH process includes that produced in the ODH reaction and carry over when carbon dioxide is used as an inert diluent. Under certain circumstances carbon dioxide can also be consumed in the ODH process by acting as an oxidizing agent. By varying the amount of steam introduced into the ODH process an operator may alter the degree to which carbon dioxide acts as an oxidizing agent. This in turn allows a level of control in the degree to which carbon dioxide is consumed in the process, effecting overall carbon dioxide output. Minimizing the carbon dioxide output provides an opportunity to limit or eliminate the requirement for release of carbon dioxide into the atmosphere.

The invention relates to a mixed oxide material comprising the elements molybdenum, vanadium, niobium and tellurium, which, when using the Cu-K radiation, has diffraction reflections h, i, k and l in the XRD spectrum, said diffraction reflexes having their apex points at the diffraction angles (2.Math.) 26.20.5 (h), 27.00.5 (i), 7.80.5 (k) and 28.00.5 (l), characterized in that the mixed oxide material has a pore volume of >0.1 cm.sup.3/g. The mixed oxide material according to the invention is produced by a method comprising the steps of: a) producing a mixture of starting compounds containing molybdenum, vanadium, niobium and tellurium dioxide as a tellurium-containing starting compound as well as oxalic acid and a further oxoligand selected from the group consisting of dicarboxylic acids and diols, b) hydrothermally treating the mixture of starting compounds at a temperature of 100 to 300 C., c) separating and drying the mixed oxide material which is contained in the suspension resulting from step b).

Provided in this disclosure is a process for the oxidative dehydrogenation of a lower alkane into a corresponding alkene. The process includes providing a gas stream comprising the lower alkane to a reactor; contacting, in the oxidative dehydrogenation reactor, the lower alkane with a catalyst that includes a mixed metal oxide; and providing to the last 50% of the oxidative dehydrogenation reactor a stream comprising from 0.01 vol. % to 10 vol. % of a C.sub.1-C.sub.3 alcohol.

The preparation of an oxidative dehydrogenation catalyst comprising Mo, V, Nb and Te using a hydrothermal step the activity and reproducibility of the catalyst is improved by conduction the hydrothermal step at higher pressures while permitting gaseous products to leave the reactor. In some instances a condenser may be upstream of the pressure relief valve.

A novel mixed oxide material is disclosed which contains molybdenum, vanadium, tellurium and niobium and the use of the molybdenum mixed oxide material as catalyst for the oxidative dehydrogenation of ethane to ethene or the oxidation of propane to acrylic acid and a process for producing the mixed oxide material.

Provided in this disclosure are oxidative dehydrogenation catalysts that include a mixed metal oxide having the empirical formula:

Mo.sub.1.0V.sub.0.12-0.49Te.sub.0.05-0.17Nb.sub.0.10-0.20O.sub.d

wherein d is a number to satisfy the valence of the oxide. The oxidative dehydrogenation catalyst is characterized by having XRD diffraction peaks (2 degrees) at 220.2, 270.2, 28.00.2, and 28.30.1. The disclosure also provides methods of making the catalysts that include wet ball milling.