A kind of preparation method of macroporous alumina carrier with double pore size distribution

Abstract

The invention provides a method for preparing a macroporous alumina carrier with double pore size distribution, which comprises the following steps: (1) Pseudo-boehmite wet mass is beaten with acetic acid aqueous solution, sprayed and dried with hot air at 400-450°C, and prepared To obtain microspherical alumina powder with an average particle size of 20‑40 μm; (2) Mix microspherical alumina powder, pseudoboehmite dry powder, and lubricant, add phosphoric acid aqueous solution, knead into a uniform mass, extrude, and dry ; (3) The dry bar is roasted at 980‑1050 °C to obtain an alumina carrier with a specific surface area of ​​40‑60 m 2 / g, the pore volume is 0.6-0.75ml / g, and has a double pore size distribution, and the diameters of several pores are 40-55nm and 0.5-2μm respectively.

Description

technical field [0001] The invention belongs to the field of industrial catalysts, and in particular relates to a preparation method of a macroporous alumina carrier with double pore size distribution. Background technique [0002] Alumina is a commonly used catalyst carrier, which is widely used in hydrogenation and sulfur recovery catalysts. Generally, pseudoboehmite dry powder is used as raw material, plus lubricants, pore-forming agents such as kale powder, cellulose, nitric acid, acetic acid Equal gelation, kneading and extruding, drying, and roasting can prepare cylindrical, three-leaf, four-lobe and other shapes of carriers. Catalysts for some uses require the use of alumina carriers prepared by calcination at a relatively high temperature of about 1000°C, taking advantage of their larger pore size, not too low specific surface area, and pore volume, and some applications also use lower alumina carriers Surfactant. [0003] Alumina carriers are widely used, widely u...

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Problems solved by technology

[0005] In the process of removing mercury from natural gas, sulfur-loaded activated carbon is commonly used as a mercury removal agent; aluminum oxide carriers are also used to support metal sulfides such as copper sulfide and cobalt-molybdenum sulfide as a mercury removal agent; the principle is that mercury and sulfur form mercury sulfide and remove it. The accuracy of mercury can reach the level of 0.1-1μg / m³ of gas, and the mercury removal capacity can reach more than 5% (mass). Influenced by moisture and easily condensable hydrocarbons, when the absolute partial pressure of moisture and easily condensable hydrocarbons is high, they can condense into a liquid state in the fine diameter pores of the carrier, such as pores below 20nm, which hinders the contact and reaction of mercury and mercury removal components, thereby reducing mercury removal The speed and capacity of the new mercury removal agent decreased in a short period of time, and the mercury removal capacity was lower than expected, so it had to be replaced frequently

Another disadvantage of the sulfur-loaded activated carbon mercury removal agent is that it will lose powder due to the impact of air flow and bed vibration during the long-term application process. Because the mercury content in the surface layer of the mercury removal agent is relatively high, the powder drop of the mercury removal agent will sometimes cause some pollution.