An alumina having a multimodal particle size distribution wherein at least one of the particle sizes giving local maximum values in the particle size distribution is less than 10 m, and wherein the alumina comprises 1 to 5 wt % of at least one of La and Ba.

The rate of release of a well treatment agent into a well may be controlled by introducing into the well a screen containing a well treatment composite having a well treatment agent and a support for the well treatment agent. The diameter of the substrate is less than the diameter of the opening of the screen of the screen assembly. Over time, the well treatment agent is released from the substrate and passes from the interior of the screen into the well.

The rate of release of a well treatment agent into a well may be controlled by introducing into the well a screen containing a well treatment composite having a well treatment agent and a support for the well treatment agent. The diameter of the substrate is less than the diameter of the opening of the screen of the screen assembly. Over time, the well treatment agent is released from the substrate and passes from the interior of the screen into the well.

The present disclosure relates to an alumina having a surface area in the range of 330-400 m.sup.2/g, a pore volume in the range of 1.2-1.7 cc/g, and an average pore diameter in the range of 125-160 . The present disclosure also relates to alumina extrudates having a diameter in the range of 1 mm to 3 mm, a surface area in the range of 300-360 m.sup.2/g, a pore volume in the range of 0.8-1.3 cc/g and pore diameter in the range of 90-130 with a crushing strength in the range of 1-2.5 daN/mm. Further, the present disclosure relates to a process for the preparation of alumina and alumina extrudates. The alumina extrudates can be used as a support for catalyst preparation or as a catalyst or adsorbent in various processes. The process of the present disclosure enhances metal loading capacity, has better metal dispersion, and exhibit delay in deactivation of the catalyst due to mouth pore plugging.

The present disclosure relates to an alumina having a surface area in the range of 330-400 m.sup.2/g, a pore volume in the range of 1.2-1.7 cc/g, and an average pore diameter in the range of 125-160 . The present disclosure also relates to alumina extrudates having a diameter in the range of 1 mm to 3 mm, a surface area in the range of 300-360 m.sup.2/g, a pore volume in the range of 0.8-1.3 cc/g and pore diameter in the range of 90-130 with a crushing strength in the range of 1-2.5 daN/mm. Further, the present disclosure relates to a process for the preparation of alumina and alumina extrudates. The alumina extrudates can be used as a support for catalyst preparation or as a catalyst or adsorbent in various processes. The process of the present disclosure enhances metal loading capacity, has better metal dispersion, and exhibit delay in deactivation of the catalyst due to mouth pore plugging.

A method of producing a highly-pure aluminum hydroxide, comprising the following steps: (1) reacting alcohol with metal aluminum to produce aluminum alkoxide, then hydrolyzing the aluminum alkoxide with water to produce an aluminum hydroxide slurry and an alcohol, filtering the aluminum hydroxide slurry, washing a resulting filter cake with water to remove the alcohol trapped therein, and drying the filter cake after the water washing to produce an aluminum hydroxide powder, (2) sending the alcohol-containing water produced in step (1) to an alcohol extraction unit for separating water and alcohol through extraction, and sending the separated water back to step (1) for recycling, (3) dehydrating the hydrous alcohol produced by hydrolyzing the aluminum alkoxide in step (1) before using it as the raw materials for reacting metal aluminum with alcohol to produce aluminum alkoxide in step (1). The method can improve the recovery of alcohol, reduce the production cost of a highly-pure aluminum hydroxide, improve the purity of aluminum oxide and achieve a zero discharge of sewage by recycling water.

A process of making a dense, cohesive and uniform aluminum oxide coating on a metallic substrate includes electrodepositing polynuclear aluminum oxide hydroxide clusters from a polynuclear aluminum oxide hydroxide cluster solution on a metallic substrate to form a precursor coating, and post-treating the precursor coating to form a final aluminum oxide coating on the metallic substrate.

A process of making a dense, cohesive and uniform aluminum oxide coating on a metallic substrate includes electrodepositing polynuclear aluminum oxide hydroxide clusters from a polynuclear aluminum oxide hydroxide cluster solution on a metallic substrate to form a precursor coating, and post-treating the precursor coating to form a final aluminum oxide coating on the metallic substrate.

An alumina composite sol composition includes (A) an alumina sol containing an alumina hydrate, (B) an alkoxysilane compound, (C) a polyvalent organic acid, and (D) a solvent, wherein the amount of the alumina hydrate in the alumina sol (A) is 3 to 11% by mass.

The present invention relates to an alpha alumina having a high purity, a high density and a low surface area and particularly, to a method to produce such an alpha alumina as well as to the use of the alpha alumina in sapphire production or the production of composite and ceramic bodies.