JP2000061307A5

JP2000061307A5 -

Info

Publication number: JP2000061307A5
Application number: JP1998246567A
Authority: JP
Filing date: 1998-08-17
Publication date: 2005-06-02

Description

（ｂ）成分の周期表２族（以下、２族と略す）、３族（以下、３族と略す）及びランタノイド金属の酸化物、又はこれらの前駆体（以下、第３成分ということがある）を用いる目的は、本発明の触媒に耐硫黄被毒性を付与することにある。
すなわち、本発明の触媒の活性成分であるルテニウムは、水蒸気改質反応時の炭素析出抑制性に優れるが、一旦、硫黄に被毒されると、この特性が弱まり、硫黄被毒と炭素析出の両面から触媒性能が損なわれるが、（ｂ）成分は、この硫黄被毒を防止し、触媒性能を維持することができる。 Component (b) Periodic Table of Group 2 (hereinafter referred to as Group 2), Group 3 (hereinafter referred to as Group 3) and oxides of lanthanoid metals, or precursors thereof (hereinafter referred to as third component) the purpose of using) is to confer resistance to sulfur poisoning in the catalyst of the present invention.
That is, ruthenium, which is an active component of the catalyst of the present invention, is excellent in carbon deposition suppression during steam reforming reaction, but once poisoned by sulfur, this property is weakened and sulfur poisoning and carbon deposition Although the catalyst performance is impaired from both sides, the component (b) can prevent this sulfur poisoning and maintain the catalyst performance.

また、担体に不溶・固定化したルテニウム種、すなわち還元処理前のルテニウム種は、水酸化物であり、この水酸化ルテニウムは、６０〜８０℃程度の低い温度領域で金属ルテニウムまで還元されるが、極めて微粒子状の活性金属の場合、極一部の活性点が熱履歴を受けることも考えられる。
従って、本発明では、実プラントで長期間安定した触媒性能が保持できるように、ルテニウム種の還元温度を、還元温度としては比較的低めの６００〜９５０℃、好ましくは７００〜９００℃、より好ましくは８００〜９００℃とする。
９５０℃を越える高温で還元を行うと、ルテニウム金属の凝集やシンタリングによる金属表面積の減少の外に、担体の細孔の閉塞、あるいはアルミナのα相への転移が起こり始めるため、触媒活性が著しく低下する。
還元用ガスは、水素ガス、水素・水蒸気混合ガス、一酸化炭素等を用いることができる。中でも、水素ガスや水素・水蒸気混合ガスが好ましく、水素ガスが特に好ましい。
還元時間は、還元温度、還元用ガスの通気量等の条件に応じて適宜選択すればよいが、１〜２０時間程度が実用的である。 Also, the ruthenium species insoluble and immobilized on the carrier, that is, the ruthenium species before reduction treatment is a hydroxide, and this ruthenium hydroxide is reduced to metallic ruthenium in a low temperature range of about 60 to 80 ° C. In the case of a very fine particulate active metal, it is also conceivable that a very small number of active points receive a heat history.
Therefore, in the present invention, the reduction temperature of the ruthenium species is relatively low as 600 to 950 ° C., preferably 700 to 900 ° C., as the reduction temperature so that stable catalytic performance can be maintained for a long time in a real plant. Shall be 800 to 900 ° C.
When reduction is performed at a high temperature exceeding 950 ° C., in addition to the reduction of metal surface area due to aggregation or sintering of ruthenium metal, clogging of the pores of the support or transition of alumina to the α phase starts to occur, so the catalytic activity is reduced. It drops significantly.
As the reducing gas, hydrogen gas, a mixed gas of hydrogen and steam, carbon monoxide and the like can be used. Among them, hydrogen gas or a mixed gas of hydrogen and steam is preferable, and hydrogen gas is particularly preferable.
The reduction time may be appropriately selected according to the conditions such as the reduction temperature and the flow rate of the reducing gas, but about 1 to 20 hours is practical.