Disclosed are ruthenium-based catalyst systems, hafnium-based catalyst systems, and yttrium-based catalyst systems for use in ammonia decomposition. Catalyst systems include ruthenium, hafnium, and/or yttrium optionally in combination with one or more additional metals that can be catalytic or catalyst promoters. Hafnium-based and yttrium-based catalyst systems can be free of ruthenium. The catalyst systems also include a support material. Disclosed catalyst systems can decompose ammonia at relatively low temperatures and can provide an efficient and cost-effective route to utilization of ammonia as a carbon-free hydrogen storage and generation material.

Disclosed are ruthenium-based catalyst systems, hafnium-based catalyst systems, and yttrium-based catalyst systems for use in ammonia decomposition. Catalyst systems include ruthenium, hafnium, and/or yttrium optionally in combination with one or more additional metals that can be catalytic or catalyst promoters. Hafnium-based and yttrium-based catalyst systems can be free of ruthenium. The catalyst systems also include a support material. Disclosed catalyst systems can decompose ammonia at relatively low temperatures and can provide an efficient and cost-effective route to utilization of ammonia as a carbon-free hydrogen storage and generation material.

Disclosed are ruthenium-based catalyst systems, hafnium-based catalyst systems, and yttrium-based catalyst systems for use in ammonia decomposition. Catalyst systems include ruthenium, hafnium, and/or yttrium optionally in combination with one or more additional metals that can be catalytic or catalyst promoters. Hafnium-based and yttrium-based catalyst systems can be free of ruthenium. The catalyst systems also include a support material. Disclosed catalyst systems can decompose ammonia at relatively low temperatures and can provide an efficient and cost-effective route to utilization of ammonia as a carbon-free hydrogen storage and generation material.

In general, disclosed herein are methods for forming hydrogen by use of an ammonia decomposition catalyst system. For instance, a method can include contacting a catalyst system with an ammonia source at a temperature of about 450? C. or lower. The catalyst systems can include a support material and a trimetallic catalyst component carried on the support material and within a reactor. Disclosed catalyst systems can decompose ammonia at relatively low temperatures and can provide an efficient and cost-effective route to utilization of ammonia as a carbon-free hydrogen storage and generation material.

In general, disclosed herein are methods for forming hydrogen by use of an ammonia decomposition catalyst system. For instance, a method can include contacting a catalyst system with an ammonia source at a temperature of about 450? C. or lower. The catalyst systems can include a support material and a trimetallic catalyst component carried on the support material and within a reactor. Disclosed catalyst systems can decompose ammonia at relatively low temperatures and can provide an efficient and cost-effective route to utilization of ammonia as a carbon-free hydrogen storage and generation material.

Organometallic complexes are described which are useful as pre-polymerization catalysts which may form part of olefin polymerization catalyst systems. The catalyst systems find use in the polymerization of ethylene, optionally with one or more C.sub.3-12 alpha-olefin comonomers. The organometallic complexes are broadly represented by formula I:

##STR00001##

wherein L is a bridging group containing a contiguous chain of atoms connecting P with Cy, wherein the contiguous chain contains 2 or 3 atoms and wherein Cy is a cyclopentadienyl-type ligand. The olefin polymerization catalyst system is effective at polymerizing ethylene with alpha-olefins in a solution phase polymerization process at high temperatures and produces ethylene copolymers with high molecular weight and high degrees of alpha-olefin incorporation. Pre-metallation compounds, metallation processes and synthetic methods to make the organometallic complexes as well as polymerization processes are also described.

This invention relates to an aqueous dispersion of particles, the dispersion having a particle content of 10-70 wt %, and the particles comprising, on an oxide basis: (a) 10-98 wt % in total of ZrO.sub.2+HfO.sub.2, and (b) 2-90 wt % in total of Al.sub.2O.sub.3, CeO.sub.2, La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.6O.sub.11, Y.sub.2O.sub.3, or a transition metal oxide, wherein the dispersion has a Z-average particle size of 100-350 nm and the particles have a crystallite size of 1-9 nm. The invention also relates to a substrate coated with the aqueous dispersion of particles.

This invention relates to an aqueous dispersion of particles, the dispersion having a particle content of 10-70 wt %, and the particles comprising, on an oxide basis: (a) 10-98 wt % in total of ZrO.sub.2+HfO.sub.2, and (b) 2-90 wt % in total of Al.sub.2O.sub.3, CeO.sub.2, La.sub.2O.sub.3, Nd.sub.2O.sub.3, Pr.sub.6O.sub.11, Y.sub.2O.sub.3, or a transition metal oxide, wherein the dispersion has a Z-average particle size of 100-350 nm and the particles have a crystallite size of 1-9 nm. The invention also relates to a substrate coated with the aqueous dispersion of particles.

Organometallic complexes are described which are useful as pre-polymerization catalysts which may form part of olefin polymerization catalyst systems. The catalyst systems find use in the polymerization of ethylene, optionally with one or more C.sub.3-12 alpha-olefin comonomers. The organometallic complexes are broadly represented by formula I: ##STR00001##
wherein L is a bridging group containing a contiguous chain of atoms connecting P with Cy, wherein the contiguous chain contains 2 or 3 atoms and wherein Cy is a cyclopentadienyl-type ligand. The olefin polymerization catalyst system is effective at polymerizing ethylene with alpha-olefins in a solution phase polymerization process at high temperatures and produces ethylene copolymers with high molecular weight and high degrees of alpha-olefin incorporation. Pre-metallation compounds, metallation processes and synthetic methods to make the organometallic complexes as well as polymerization processes are also described.

A catalyst comprising: a titanium oxide having an anatase-type crystal structure, and having the vertices and the ridge lines, wherein in a single titanium oxide particle, a vertex density per unit surface area is 8.010.sup.4 nm.sup.2 or more, and a ridge line density per unit surface area is 5.010.sup.2 nm or more, or a ridge line density per unit volume is 8.010.sup.3 nm.sup.2 or more. A complex comprising: a material having a porous structure; and said catalyst. A membrane electrode assembly comprising: an anode; cathode; and an electrolyte membrane, wherein the cathode carries said catalyst on at least a surface of the cathode.